Thalassamania:When we were working on a standards rewrite for one of the major agencies we tried to insert a clause requiring that there be, at a minimum, one confined water session (prior to going to open water) in the same full gear that would be used in open water. This recommendation was rejected by the agency as non-competitive since it would make their courses more expensive.
I think the idea is good but there is a reason that it wouldn't have worked for us and it had nothing to do with competing.
First, some of the pools we used were just too watm to put some students in two piece 7 mil suits. Second, the pool really does ruin a wet suit in a hurry.
On the other hand we used other pools that were pretty chilly and some students needed exposure protection...I know that I sure did.
What we used to do is start OW weekends with a session in shallow pool like OW conditions with the sole purpose of getting them weighted, trimmed and acclimated. Only then did we start OW training dive 1. If it took an hour and a tank of air, then that's what it took but I wasn't taking any one out diving until it was done.