All my birds have their own cages. They spend all day outside of them as a rule. So the size of the cage isn't nearly as important as it would be if they had to spend a lot of time locked up.
That being said, Ringo has a huge flight cage that formerly belonged to the budgies, before Benjy decided to be tame (it was HIS decision) so he could come out and I had a chance of putting him back in at night. So he's got a small cage now to sleep in. Ringo lives in the back bedroom with my lizard and his worms. It's not a very big room, and that huge cage, though she does use all of it in her bouncing around and playing, takes a lot of floor space. I am considering moving her back into her first cage, and either selling the big one or giving it to Freddie and Johnny to share and selling their cages. Freddie and Johnny are best buds and do everything together and spend a large portion of their days together in one of their cages playing and tearing up their newspaper. Near bedtime, they usually take up posts in one cage or the other and start settling down to sleep, but that's with the door open. I don't know what they'd think of having to spend the whole night locked in the same cage. I suppose I could do a trial run and if it doesn't seem to be working out, put things back the way they are now. I'm just trying to figure out a way to save a little work and one fewer cage to clean would be nice, as well as having some of that floor space back in the back bedroom. That's also the room where I keep my clothes and dressing table and do my music practicing.