As stated earlier, there are too many variables to give you a pat answer.
What I have noticed is that there's an inverse proportion between starting level and how long it takes to drop. Going from 100 to 90 will take lots longer than going from 180 to 150. The more vigorous you agitate, the faster it drops. If I run all the output through my spa, and run the booster, it looks like the thing is boiling. And then it spills over into the pool, and you can actually see bubbles rising from 4 or 5 feet down. I've lost 30ppm TA in 5 hours before, as an extreme example. It also goes faster the lower the pH is. So if you keep adding acid to keep it down close to 7, rather than waiting for it to climb back up to 7.6 or so, you can speed things along.