To be honest... I rarely go to the pool in the off season. I get to a point where I dread it if I swim all the time. So maybe once a week- or every two weeks if I have no races scheduled. But as soon as there is a race on the horizon I'm back at it. I find that it's the easiest to get back after a lay off.
BUT I am starting some heavy duty swim coaching here in the next few weeks, so I suspect I'll be in the pool A LOT trying to hone my new tecnique.