JeffG:
The problem with doing that way, is finding a buddy for the second part of the class.
In Andy's neck of the world, buddies are plentiful.
I took mine in Ontario. The 3 of us had never met or dived together before.
Since we all had the same "basic training" via DIRf, we somehow managed to get it together. The TDI guy brought the "every dive is a solo dive, heck with your buddy, every diver for himself, only you can do your deco, independence for every diver" attitude with him. The other 2 of us worked pretty hard to get him to remain part of the team even when he or we were having a "problem."
By keeping the team together, every 'problem' the instructor threw at us was easily solved into a non-problem, even when there was more than one at a time (i.e. a team member with no gas, no mask and doing deco. It's up to the other team member(s) to help him/her get to the surface.
By looking out for each other, we were even able to avert some of them. Whenever the team started falling apart, the problems compounded and someone got in "trouble." There was much emphasis on thinking about everything we do and everything that happens. Sometimes the automatic or instinctive reaction is the one that's going to hurt someone. It was no "vacation" by any stretch of the imagination.
As for taking time off Andy - depending on the schedule of the instructor, some of these classes can be done as a long weekend, so you can do them with only a day or two off work. Most employers allow a personal day or two in addition to vacation time, don't they?