I struggle with this for my personal computer. The TV-computer combo shuts off the monitor (triggers the tv to shut off when there is no input) after an hour. An hour after that it's suspended, works well.
My personal computer though, sometimes I shut off the monitor, most of the time I let it run for the day completely powered. I have yet to set any type of shutdown or standby because typically I use it more than I do my tv (work, gaming, videos, etc on the comp). I know there's some power conservation I need to consider for motivation, I have no security concern atm with my standard main account and everything private is layered so inaccessible.
tl;dr
what's everyone else's setup like for when they walk away from the computer?
After 30mins of inactivity my account locks and my screens blank. Few seconds after that my monitors go to standby. That's it. I never shutdown unless something necessitates it and I only really reboot for updates if they require it. My PC basically stays on 24/7 and I've never had any issues. Current build has parts all the way back from 2015/2016 with no failures to speak of.