I agree you should shift each engine into reverse, checking for operability and mechanical soundness, but 3 times is excessive, even OCD. At this point you are shifting it around until something breaks, not checking for something broken. Once is prudent, twice is cautious, but thrice is excessive wear. If you hear something you are unsure of and want to check again, that's different, but otherwise get on with it.
I agree you shouldn't come roaring into the marina assuming everything works and everything is the same as when you left, but letting your boat drift around the marina for 45 seconds: either the current and wind are not significant or you'll see it in a lot less than 45 seconds (10-15 perhaps?). Fine if you are teaching someone boat handling and no one is around,
but good seamanship also means not needlessly wearing out your boat and not drifting around blocking up a marina (not saying to let others rush you, certainly take the time you need, but you can be motoring slow ahead and still watching wind and current). Especially in a river marina in a city with wind shadows all around, (Thinking Vancouver) where both wind a current can be very different in different parts of the marina, I don't believe drifting around one spot in the marina to be of any significant advantage considering the great variation that may be present, and could actually put someone into a situation where they are fighting to recover control of their boat rather than working to maintain control of their boat.
Respectfully
Wilf

Everyone in America has a boat in a marina