Q. Common or rare?
A. Common - we'd lock all tasks before a release.
Q. Lock comments? Do you need to lock comments too, or just other types of edits (like status, priority, title, description, etc)?
A. I'm ambivalent about this, if the lock is mandatory then being able to add comments seems reasonable since someone can point out that the task needs to be unlocked for some reason or other.
Q. In particular, could a solution where anyone could unlock the task be acceptable, as long as they had to explicitly unlock it? Or is it a hard regulatory requirement that unlocking requires some sort of administrator/oversight step?
A. Unclear, I'll ask, but it's probably fine since there's also a 'process' that states how people use the system. (And you'd be surprised how much drama there is inside private companies:-) That is, our conventions are formally documented and people expected (and expect) to follow them.
Q. Lock other objects?
A. Possibly, but I've been pushing back on it for things like code reviews by arguing that 'everything is logged and there's an audit trail' so what does a lock by us? Obviously locking git doesn't really make sense and new comments can't hide old ones so I don't see what the problem is. For tasks, I don't feel I can make that argument since people will naturally just look at the current state of the task unlike code reviews where the history is 'in your face' as it were.