It depends on the house. A 2 story house with basement would have wire pulled up to the first floor from the basement and dropped down from the ceiling for the second floor. You would either pull all the wire to the attic through a central wall plumbing stack or run up the side of the house in a conduit.
You wouldn’t follow the original lateral wiring paths through the wall but do that either in the basement or attic in junction boxes.
I don’t use aluminum wire but it sounds right that it’s softer, more flexible, and easier to pull, plus easier to close up crowded boxes. I really doubt the difference in weight itself makes much difference in carrying the wire. It might mean one extra trip to the truck to carry in the heavier copper, 5 to 10 minutes added to the job tops.
And besides the pulling many electricians, and non-electricians like me, will roll out the cable and let it sit for a while to straighten it. That is probably easier or maybe unnecessary with aluminum.
Well, it’s better than nothing.
That’s about all that can be said for it. Sometimes the center screw is actually grounded, sometimes that pigtail makes a good connection to the center screw, sometimes it doesn’t get knocked loose by someone, etc. So there’s a chance it might do some good.
Here’s my aluminum story.
I got a new oven once and had it professionally installed. A few years later, the subpanel breaker feeding the oven started tripping randomly. I did what I could to troubleshoot but couldn’t figure it out, so I thought the oven was just going bad and got a new one. I installed this one myself. When I pulled out the old oven, I made a few discoveries. First, previously unbeknowst to me, unlike most of the wiring in the house, the line from the subpanel to the oven is aluminum. Second, the “professional” who installed the old oven connected the aluminum line to the oven’s copper wiring with WIRE NUTS, which even I know should not be done. And as a demonstration of why this is a bad idea, the plastic on one of the wirenuts had MELTED, exposing bare wires, which is why the breaker kept tripping.
I talked to several electricians about what was the best way to connect the aluminum line to the oven. I finally settled on Polaris connectors, which was recommended by the most knowledgeable guy I talked to. He recommended that I coat the end of the aluminum with some dope that keeps the oxygen out (I forget what it’s called), sand the aluminum to remove the oxide coat, put it in the Polaris and tighten it down, and then (very important according to him), come back and retighten a few times, spaced over a few hours, so that the connection doesn’t loosen due to the aluminum’s cold creep.