When does diffusion stop?

I’ve read that some mones last a long time and others you have to reapply often. I understand that fragrances last for different amounts of time for different people.

If I can still smell the bonded fragrance, is the associated pheremone still diffusing? Do they eventually separate and are you left only with the fragrance?

Thanks ..

No - IME, the fragrance usually fades before the mones are done. Except for the shortest acting ones. Then the all the personal and environmental factors play their part.

It just takes a bit of time and practice till you spot when the effects are beginning to tail-off and its time to topup/refresh.