I'm relatively new to production Mikrotik deployments and I'd like to know how reliable are RouterOS updates. When a new version comes in stable or long-term channel, is it safe to update remotely? It would be very inconvenient for me to travel all the way to the site and bring the device back online. Have you ever had a case when you updated RouterOS and after the reboot some things weren't working anymore? What is your update policy?

"Stable" often introduces regressions, rarely has this resulted in total connectivity loss but I generally stick to long-term on remote devices unless there's need for a specific change. Unless it's a security related fix, I would also wait a few days for bugs to be reported by others before upgrading.

I've only been on the receiving end of one fault in about 2-3 years of using mikrotik's, and all that did was make the USB connected modem run very slow, so I could have still fixed it remotely if I wanted.