How to make FFM stronger

I saw a hack on here a few months ago where a woman said her daughter left her FFM in her car and it was much stronger than her FFM (same scent) that was properly stored in a cool place.

My car is always parked in a garage but now that the weather is heating up, I decided to leave several bottles of FFM on my deck. I’ve done it for 3 days now and it’s definitely working. I wouldn’t say they last all day, but I can definitely smell them for a few hours now and they’re much stronger. Even ATW which I usually can’t smell after 5 minutes, lasts and has good throw. Planning to put them out again for two more day.