1972 house. Master closet is 6 x 6’
My wife has taken over every closet in the house, plus two spare rooms, and has her eyes on my man-cave garage.
I am trying to hold out but am learning that resistance is futile, the garage will be assimilated.
Our house was built in 1904. My personal closet was meant to be the coat closet, which means I get dressed in the front room. It’s a small walk-in, with about three and a half feet of clothes-hanging space to the right of the door and enough room for my dresser to the left.
The other two closets are upstairs in the bedrooms. They each have tiny dormer windows. The slope and angles of the roof cut down a lot on usable space but there’s about five feet of space to hang clothes in each of them. Hubby has lived here a lot longer than me. Those closets (and the second bedroom) are pretty much full of stuff already.
I have a 1983 townhouse. Our condo development actually did a decent job with closets. My bedroom closet runs the full width of my bedroom – I’d guesstimate 10 or 12 feet. It’s not a walk-in. When we remodeled about ten years ago, our GC took out the wonky hanging thingy (you had to hang the hangers backward) and weak shelving, and replaced them with full plywood shoe shelving, solid maple hanging bars, and additional shelving in an area to the side on the left of the opening and was kind of a black hole before.
Mine is roughly 10’x12’. I have a bed in there and it doubles as my guest room and yoga room. The actual closet part, a wall and a half of built-in hanging racks and dressers, takes up less than half the room.
I love it. It’s very private because you have to walk all the way through my bedroom, then all the way through my bathroom to access it. I had some concerns about using it as a guest room because there is only one entrance and no windows and I’m freaky about safety.
So I keep a big axe in the corner and I’ve marked the spot where there’s an unobstructed space on the other side of the wall in the garage. In an emergency, I can make my own exit. Someday, I’m going to cut a section of the wall out and put hinges on it but I haven’t gotten around to it.
You and I understand each other. She has well and truly started in on my Sanctuary.
I’m probably down to 1800 sq feet already.
I’ve lived in places with no, or tiny, or adequate, or huge closets. Whatever. Our current (since 2002) mountain “cabin” is a trailer - well, a triple-wide modular of about 2200 interior square footage. The master bedroom’s walk-in is about 5x13 feet with doors ar each end. The secondary bedroom’s squeeze-in is about 3x9 feet with mirrored sliding door for that erotic zest. A 20-foot shipping container came with the property; that’s our extra closet space. The closet in the 25-foot-long RV might be 15 inches square and 3 feet high but the bathroom is large. 
Nearby inlaws live in a mountain McMansion. The finished basement is their extra closet. Wow.
Swiss homes do not have closets in the bedrooms. We have a wardrobe and 2x dressers in our bedroom.
There is a linen closet in the hallway, where all the cleaning supplies and vacuum cleaner lives and a closed in the foyer, which has coats, bags (camera, hiking backpacks, etc.) and the recycling.
When we bought this place, before we made the closet changes, all the doors were mirrored sliding panels. That resulted in a mere 18" actual opening, so storing larger containers was pretty close to impossible. The hall closet now has a full-width door, and the bedrooms have bi-fold doors. Not my favorites, but they use minimal floor space, and we have nearly the full 3’ open. We also added shelves to fill the void in the top of the closets and add storage space.
When I inherited my mothers house, the master bedroom has two walk-ins, each big enough to drop a twin bed in and have room left over. The second bedroom has a small walk-in, maybe 5’ by 7’. Two years, and I’m still donating her cloths.