I cannot say much with any confidence because I started revisiting FreeBSD after a long (like 15 years! :) ) absence. However, from what I see there are ways to mitigate issues that might occur. For example, doing a ZFS snapshot before doing a package update can be one thing to do. I think if you have a cluster of machines, doing a canary update with the option to rollback sounds like something that would ease the mind. I think also the tooling will allow you to control any bulk updating. This is in fact what I was starting to play with today - new port updates are available, how do I do selective updates? It's possible, but some reading of the handbook and/or man pages will get to that answer probably.