I would immensely disagree that most teams only bring up their prospects for permanent stays.
I didn't say that most teams did that. I said most good teams. Just as earlier I didn't say all prospects as you claimed, but top prospects.
Yes, it common practice for teams to bring up prospects for short stints to see if they are ready, but it is exactly that which the Leafs' claimed they were getting away from in favour of keeping top prospects down until they know they are ready. It was exactly this reason why they brought in a lot of depth so they wouldn't have to use their developing prospects to cover for injuries or fill in holes at the bottom of the roster.
It's laughable that people think that this stint has provided anything of value.
An injury to a D or two occurs.
Who can bring up?
Well Sandin has some experience in the NHL.
Great. How was he on the PP?
He is good at it in the AHL.
NHL?
Don't know.
How was he on the PK?
He is good at it in the AHL.
NHL?
Don't know.
How was he if he needs to play more minutes?
He is good at it in the AHL.
NHL?
Don't know.
How was he defending a lead?
He is good at it in the AHL.
NHL?
Don't know.
How was he when the game is tied?
He is good at it in the AHL.
NHL?
Don't know.