Every event in AdVenture Capitalist has its own unique balance which means the Profit Booster per event also differ. 

You might think some boosters aren't working and so it's important to remember that the boost varies per event and different profit boosters have different “weights” to how much time is given back per tap. Those where it looks like it's standing still just have less time given back per tap, so you need to tap it even faster.