I'm looking for catastrophic leaks, and it's usually pinch time getting ready for a race. And these motors have been tested before with a several minute test.
I have let some motors set on the bench for several minutes and not saw a drop in pressure, and I keep a good enough eye on plugs to see a possible leak. I have retested at the track on a few motors, and I never find a leak.
Now if it was an unknown motor, I would make damn sure it is tight.
But all of mine have been tested every time I take anything off, so when I say I just let it set for a minute, I'm just making sure I didn't fubar anything whilst I was being a parts changer.