Some guys get 'blocked legs' if they take two complete days off the bike, so they like to do some 'openers' the day before. I personally don't have this issue, although I do extend my warmup a bit longer than normal on race day so they are fully open by the start of the race. Especially before something like a 60 minute crit where you don't have time to warmup during the race.
I say no vo2 specific intervals during the week, just do them during the group ride, at least for new(er) riders. You will be going to vo2 max / anaerobic a LOT if it's a hammer ride, especially if you're a cat 4 or 5 (heck even cat 3's if they are riding with a bunch of 1's and 2's or other strong 3's). The time would better be spent building your aerobic base and threshold power. However, for those that can't get in group rides, or those that are too fast for their group, then yes, they probably need to set aside some time to specifically work on vo2 specifically.