In general younger males are going to have higher pheromone production but there are various other factors besides age that play into it such as diet, exercise, blood type, etc. It’s going to be a bit different for everyone which is why it is important to test for yourself. This post offers a pretty good guide to that: How to find your sweet spot...
Personally, I’m 23 and I’ve found that I don’t really want to wear more than 1 spray when out and about. I’ll take it up another with my girlfriend since we’re already in a sexual relationship and she wont be easily offput by the none.