Enough so that they should sit their boss down and say 'I have capacity for N of these projects, let's rank them in terms of priority.'
Part of it was me not handling certain kinds of stress well, but a different management approach absolutely could have made a difference. To cut them a bit of slack, this particular boss had come from a prior position where they were managing hundreds of roles... to a small shop where they managed just a handful (and only one other dedicated IT person). They had trouble breaking away from the "throw everything at the wall and go full steam on it all" approach and dealing with scarce resources more carefully.
That transition can be super super painful as you don't quite have enough work for the dedicated person.