I try to restrict projects to 24 tracks, maybe it's a throwback to my analog days? I record on a Tascam MX2424 and the track count is 24. I do have 3 machines so the track count could be 72, but I like mixing in the analog domain and the console is really being pushed when 24 + tracks are being played back.
I sometimes get projects bought in for me to mix and if the track count is high or the project is one that will keep coming back for tinkering (if I get that feeling) than i'll mix in the box.
I find that the more tracks you have the bigger temptation there is to fill them, I used to run a 16 track tape set up and on track was timecode for syncing the automation on the console and running midi so it was 15 tracks max, a lot of albums were recorded on that tape machine, you find ways of accommodating extra stuff, like recording as guitar solo where theres no vocal on that track, sub mixing the toms on the kit, mixing a string section while actually recording it. I know it's not ideal but it teaches you to trust in what you do, the Beatles recorded on 4 track, added things by sub-mixing along the way to a second 4 track and adding another 3 tracks, many classic albums were recorded on 8 track machines.
Maybe recording engineer students should be given a project like this in the course to teach them how to create a project with restrictions, it certainly teaches you about getting the most out of gear. It's actually a beneficial challenge.
Alan.