Are days off sufficient recovery when swimming 3days/week?

The club I swim with and help coach only swims three days a week. As I read the literature on daily and season planning the need for rest between high intensity workouts mostly deals with two workouts a day swimmers. If you have a day off between any two workouts does that give you enough recovery time such that you can you put in high intensity sets every workout? Likewise in season planning you often see a few weeks of hard training and then a week of recovery training. Do three day a week swimmers actually need a recovery week or do they not get sufficiently broken down to need one? On a slightly different topic, do people find it is more difficult to carry technique progress forward when only swimming every other day? Because I have a long drive to the pool I've been swimming longer workouts every other day and I'm getting rather frustrated with my lack of progress with butterfly. I improve through the course of a workout but then when I come back two days later I seem to be back at square one.