I have a 2012 and a 2018 Mini. Every now and then, I run into a problem for which the solution is rebooting - but the time is usually kind of inconvenient. Both of these are pretty much “always on”, so there’s no natural point when the computer would be shutting down anyway.
Anybody have a suggested interval?
This is no doubt a hold over habit from my Windows days but I reboot every Monday morning just for good measure. It takes 2 minutes or less.
My 2011 Mac mini use to get “issues” if it went too long between reboots. I could go a couple of weeks, but then something weird would happen, and a reboot always fixed it.
Eventually I just went to System Preferences » Energy Saver » Schedule… » and set it to reboot every Monday at 4:00 a.m.
The only glitch is that there’s no way to automatically log back in after a scheduled reboot, so I also had a reminder for 9am on Monday that said “Log in to server” to remind me to screen share in and log back in.
As little as possible.
I shut down my work MacBook Pro when I finish work every day and start it when I get up in the morning.
I reboot my MPB 2019 about once a week. Sometimes a few days less; sometimes a few days more.
I never reboot without a reason, but I do shut our computers down when we’re going to be away from home for more than a week, which has been surprisingly often over the past year.
It used to be twice a day (when going between home and work) but now it’s about every two weeks so so.
I shut down every night.
And your Mac? 
Haha my Mac too. 
A couple years ago (and on a different computer) my RAM got corrupted and my Mac would crash frequently. I found that turning it off every night would decrease the frequency of crashing (and that auto save really works). I’ve been shutting my macs off every night since
I do the same. Interesting, I do not have to log in though. The mac automatically logs me in.
Mainly when software updates require it. I have 3 Macs, an Air, an old iMac, and a Mini used as a server. The Air has been running for 25 days. The Mini is 20 days due to a shutdown to upgrade the UPS to a larger model. The iMac is only at 5 days because it was unplugged to get the old UPS from the Mini.
I normally only reboot when something goes wrong or a software update requires it. I’ve been running this version of the OS (creaky Mojave) long enough that I’ve figured out how to fix most of the “something goes wrong” without a reboot - so it’s usually months now.
Well, not this time of the year. The power doesn’t stay on that long here during winter storm season (22 days since the last extended outage/shutdown).
I basically only reboot when I must, like system software updates. My server Mac mini doesn’t get software updates (it’s too old) and its uptime is now 244 days.
You must have it on a UPS.
I reboot everytime I finish my work, and/or if work colleague ask me to join a GMeet / Zoom.
“Please wait less than 5 mins, my fan is at 6000RPM and I need to cool my laptop down first.”
I reboot all Macs and all iOS devices every Saturday morning. Then I back up the iOS devices to my main Mac.
I reboot the MacBook probably every day … it sends me warning messages when I try to eject the USB drives and it doesn’t think I have … so when I move it away from desktop to favorite chair, I shutdown and restart when in favorite chair. iMac stays on for days/weeks until something flakey starts and first step to debug is to re-boot, which more often than not the flakey-ness disappears.
Daily. Sometimes multiple times per day. Unfortunately. Have to do that to revive the wired ethernet connection introduced with Big Sur 11.2.1 and still there in 11.2.2 and 11.2.3. 
