Bush didn't have a problem seating people: wait until Congress goes on recess, then appoint by decree.

Not going to work anymore. Congress has learned to never recess - they just gavel in pro forma sessions, and never give the President a chance for recess appointments.

Of course, if Trump the Magnificent does not have that much patience, he can appoint "acting" officials.

True, but you're going to start to run out of those folks. There's a limited pool of folks who can be "acting" officials and then you need Senate-confirmed people to fill the roles they used to serve. And there's a reason none of those folks was in the top spot to begin with - they're people that Trump is okay with, but not his first choice.

So for the really key spots in the Cabinet, better to get people to either commit to staying through to the end or let you know if they're going to leave, so you can plan for it. And for the important Cabinet spots, maybe ask them to announce they're leaving now so you can have a GOP Senate to move their replacements.