ORIGINAL: DCWhitworth
Since there is a bit of dispute as to whether this 'rule' is good or not I think the best solution is to change it so that garrisoned depots *don't* stop movement then you can create a house rule if you want.
And garrisoned depots are *much* more powerful than screening corps simply because there are so much more of them and they are easily replaceable. If you kill a corps it's gone for three months, kill a depot and it can be back next turn.
PLUS no PP cost when using garrisoned depots as screens <-- BIG bonus to defender
Cheers,
Ted