Just to let you know, Jeane Dixon passed away years ago. 
I haven’t been to a wedding for years, but there was a time when they were more common in our social calendar (haha).
Rehearsal lunches are not a thing here and only seem to happen in American films. Stag and hen parties do happen, and there was a time when they were getting out of hand for ostentation and cost. I don’t know what the current situation is.
The most common format seems to be to schedule the wedding for late morning, followed by a more-or-less traditional wedding breakfast with speeches and cake cutting. This is followed by a more relaxed party in the afternoon/evening where they will have a buffet but limited or no free drinks.
For many people, the “wedding” is more a legal move at a register office with two (legally required) witnesses and no other ceremony.
In my circles, weddings are usually late afternoon, followed by dinner, with speeches and cake cutting. I don’t think I’ve ever attended a “wedding breakfast”.
I have been to a bunch of weddings, wedding ceremonies, and wedding parties, but never a wedding rehearsal. What kind of events are people having that you would need to rehearse to keep from fucking up your own (or your friend’s) wedding??
A wedding breakfast is the formal meal served immediately after a wedding ceremony in the UK. It was usually a sit-down three-course (or more) meal shared with your day guests, but despite the name, it has nothing to do with morning meals or eggs and bacon. The term dates back centuries to when couples would fast before their wedding, and this first meal together “breaks the fast” as husband and wife.
We rehearsed. It didn’t take very long. We didn’t read or say anything, just walked to spots, and said what would happen. But that way everyone knew what would happen when. You don’t want to take out the rings before the blessings, or whatever. 
It serves the nontrivial secondary purpose of making sure everyone you expect to be in the wedding party is in town, and doesn’t show up late. I think the “rehearsal dinner” is more important than the actual rehearsal.
Traditionally, for one thing, events involving children, who may not know from prior experience what to do when you’re being a bridesmaid or ring bearer, etc.
Wedding rehearsals are a longstanding tradition in US culture, but yeah, generally you wouldn’t have participated in one unless you were actually in the wedding party for a traditional-style ceremony, usually held in a house of worship. (Clergy officiants tend to support rehearsals because they have seen firsthand all the myriad ways that nervous people in unfamiliar clothing can make awkward mistakes when trying to follow an arranged sequence of even simple ceremonial actions.)
I am someone who would definitely appreciate a rehearsal. I am usually nervous about participating in any type of ceremony or show. It’s one reason why my husband and I just went to a chapel with no guests.
Wouldn’t even have to be a traditional wedding in a house of worship - my daughter’s wedding was outside the barn where the reception was held. And even if it’s a “traditional” wedding in a house of worship, it’s entirely possible that some in the bridal party have never been to that sort of traditional wedding before. My Catholic wedding was the first in my group - and I’m almost certain the two Jewish guys in the bridal party had never been to one before.
We had a rehearsal dinner paid for by my parents. There was no real rehearsal, it was mostly an excuse for them to do something for the wedding which was planned and paid for by ourselves.
It was about a dozen people, all family members. We took advantage of it being planned ahead of the time and had it at a Cantonese restaurant we favored, met with the manager beforehand and picked out a good variety of dishes including Peking duck.
Every wedding with bridesmaids and groomsmen is a little different, and odds are that only the bride and groom know everyone in the wedding party. At the wedding rehearsal you pair up the bridesmaids with the groomsmen (adjust as needed for same sex ceremonies), figure out the order, decide who escorts the groom’s elderly grandmother and where the bride’s stepfather will be while her actual father walks her down the aisle, and practice everyone walking down the aisle and walking back at a speed fast enough to keep moving but not so fast that everyone slips because their new shoes don’t have any traction on the highly buffed floor.
It’s all about logistics, and it shouldn’t take more than 15 minutes. Then everyone goes out to dinner.
Sounds to me like the whole thing could have been a group chat. I mean, practicing walking? You walk, you smile, you wave, everyone cheers. It’s not something you need to practice.
It’s been a few years but I assume the format is generally the same.
Bachelor and bachelorette parties about a month before the wedding, often destinations like Vegas or Miami. The Hangover style night before bachelor parties are usually pretty rare for obvious reasons.
About an hour rehearsal for the family and wedding party so everyone knows their places and the flow of the ceremony.
Rehearsal dinner for family and the wedding party the night before.
Destination weddings may have various other events and activities for guest prior to the big day.
The wedding itself,
Wedding photos for the couple, party, and guests
Reception
Often an optional breakfast or brunch the next day where people can hang out before their flights or whatever.
I don’t know about “sleepovers” but one couple I’m friends with had a sort of “mini bachelor/bachelorette parties” the night before where the men and the women all went out drinking in two separate groups.
That’s the general itinerary, but people can certainly modify it as they want, depending on preference and finances.
I have been to nice evening wedding receptions with (obviously) free food and drinks provided, but I do not recall any kind of explicit provisions for people too drunk to drive home afterwards, like a sleepover.
I think it’s just called “booking a room in the hotel”.
As i said above, the major value of having a rehearsal the day before is that it means everyone has to get there in advance.
But many people have a better kinesthetic than verbal memory, or at least, remember stuff better if they’ve interacted with the info in a way other than just reading/hearing it. And it’s best if you work out in advance who walks in what order. It shouldn’t take more than 15 minutes.
At the last wedding i helped organize, the venue wasn’t a hotel. And the father of the bride (whose family included a lot of serious drinkers) arranged for a bus between the hotel and the venue.
The groom, then the bride. There. Worked out.
I mean, it’s a wedding, not a production of Verdi’s Aida.
Hey, we’re trying to fight the ignorance here, not encourage it. No, a ceremonial wedding procession where a group of people are supposed to go in a certain order at specific intervals down an aisle and end up in a certain configuration at the end of it, often synchronized with accompanying music and/or including the arrangement of some fancy details like a wedding gown train, is not “just walking”. A lot of people would screw it up if they tried to perform it for the first time never having seen the venue or heard the music or seen their procession partner, if any.
(And waving and cheering? In a wedding procession? Wtf? I’ve been to a couple dozen weddings encompassing four or five different religious traditions and national customs, and I’ve never seen one where the wedding procession waves to the congregation or gets cheered while approaching the altar or other ceremonial site. Maybe some clapping during the recessional after the ceremony’s performed, but not participants waving to people like a homecoming queen on a parade float.)
Depending on the layout of a venue/chapel/building, there can definitely be miscommunication and misunderstanding.