Part 1: it takes as long to cure as it did to get there. The body is like a ship moving through the ocean. You can change course a little with no problem, drastic changes are taxing. So if you had a back injury last weekend, you’ll only need a few treatments. If you’ve had problems since college, it can take several weeks to get the ship back on track.
Part 2: for acute issues, frequently for short time (1-3 x week) for chronic, once a week for several weeks.