Me too. They changed the booster from "reduce time", where you could, with each choice of that booster, see exactly how much time you were cutting off completing the task, and see exactly when you had reduced the time enough to get three stars. They have replaced it with a super combo booster, which is harder to tell whether it's enough for three stars. It's frustrating. I've wasted a lot of that booster because you can't tell up front what the effect will be. It says "x6" or "x14" but that does not seem to actually multiply the score by those amounts.