Depends on the subject matter. How much do I love whatever it is that's being modeled? If it's something that really gets my creative juices flowing, I'll find the display space and I'll scrape together my change to make it happen. I don't really build stuff "just to build stuff." So, that 1/72 A400M from Revell? The 1/100 Master Grade MSN-06S Sinanju from Bandai? (a Gundam model, if you're wondering)? The 1/16 SU-100 from Trumpeter? Yes, yes, yes. The only thing I won't build is 1/48 armor, because all of the other armor I have is 1/35 and they'll look out of place.

If it's a model of a vehicle one of my relatives operated / worked on, well, no scale is too big.

I am in both camps so to speak, 1/72 for convenience but 1/48 for sanity.
Although saying that I have some bigger scales in the stash.
Living in a 1 bedroom flat does leave a lot of room for displaying finished kits.
Also the bench is a bit cramped when building the larger sizes.
As long as people are happy in what scale they prefer that`s what counts.

Simon.

That's a good point George! I've got about 4 1/32 aircraft in the stash, and I know when I build them there won't be a lot of display space left. They are single engine WW2 fighters, which are a decent size when complete, so something like a JU88 or He 111 would be great to build but difficult to display for me. I stick to larger aircraft such as the B-17 or Lancaster in 1/72 purely because of the size of them.

With my main frame of interest, 1930's - 1970's U.S. aircraft (mostly), subject drives the scale. Bombers, jets from the mid 50' on, and other large aircraft - 1/72 - 1/144. Bi-planes 1/32, everything else in 1/48. Armor 1:35, ships 1/350, and Sci Fi spacecraft what ever scale they say it is.

I entered the hobby when 72nd scale was still the only scale for real modelers, but I started with 48th scale because bigger was better for me at that time. Though I have occasionally built in all the scales, the bulk of my completed projects that have been kept for display through the years continues to be my favorite 48th scale. I admit that with all the focus on 32nd scale in recent years, I have been tempted more than a few times because of the added detail the larger scale allows and the state of the art of kits today. Display space becomes a factor as I find it very hard to recycle my older projects to make room for the latest completion. Though I do not have every model I have built, I do still have a few from 40 plus years ago still in the showcase. I find that having models on display in the same scale, illustrates the differences and progress in aviation design.