Size does not matter.

I picked up the biggest tower I have seen. This is just a tower computer NOT a server.
The thing is 3 feet tall. My step son was thinking it was going to have the mother load in it. So we opened it up and it had the normal size motherboard, Hard drive, 2 floppies dirve.
After he saw that and all the EMPTY space he asked why. I lokd him last owner was making up for something
As a joke I showed him how I could fit another newer tower in the empty case and it was still have empty.
It did have a 486 in it and 4 finger boards. and it is empty empty so it is still not that bad for scrap.

Huge cases like that have a lot of open space for airflow/cooling purposes. Old computers where you would have a bunch of expansion boards and extra drives left some space for extra stuff, and they couldn't always be designed to get a 4" fan moving air out of there too easily if they were packed full.