I have LI, and use Tazorac as my primary treatment. It clears my skin completely, except for the elbows, knees, and feet (which require scrubbing). I use it over the entire body (sparringly) every four days, 1/2 hour before I bathe. It removes almost all buildup, and stays that way for most of the following four days, although there is some peeling by the fourth day. I use it more frequently on my face (every other day), also 1/2 hour before showering. I've been using it for 8 years with no side effects. It's also minimized my bathing time to about 5 hours a week, and I no longer have to scrub except at the elbows, knees, and feet.
I had to use it more frequently when I first began to clear buildup, but gradually worked out the routine that minimized my use of it, while keeping my skin cleared.