The only time I noticed this was in YOW on the way to YYZ. There were approximately a half dozen uniformed staff (pilots and fa's) waiting somewhat close to the gate.

As I was working to get my upgrade at the counter, I overheard the staff conversation saying that there was a chance that all would not make it on the flight as it was pretty full. Sure enough, one of the FA's did not make it on board. Two pilots and two fa's made it up front, one was sent to the back of the bus. I did sit in front!

I expect that given that there are hourly flights between YOW and YYZ that the last fa made it back later on.