The drop, not the brush.
Most bad touch-up is not a color problem. It is a volume problem. A fluid writer pen puts down a line as wide as the tip, and the tip is wider than most rock chips. So the paint lands on the clear coat around the chip, domes up, and now there is a bump where there used to be a hole.
Precision touch is putting the paint where the chip is and nowhere else. The tool for that is the paint bottle itself, with a precision tip on it. The tip is the applicator. No brush, no pen, nothing to load.
Old wax and road film are why touch-up lifts. A white towel should come back white before any paint goes on.
Light squeeze, the tip rides in the chip, the paint goes where the tip is. Small chips take a touch. Bigger ones take a short drag along the floor of the chip.
Do not brush it out. The paint flows to the walls of the chip on its own. If it domes, that is fine. If you got some on the clear coat, that is fine too. Leveling takes care of both.
That is the whole rule. Not a timing window, not a stopwatch. Dry to the touch, then level it.
What I actually reach for is the bottle with the precision tip on it. That is the tool. The Monkey Finger is not what I use most of the time, and I am not going to pretend it is. It is the perfect replacement if you are stuck on a fluid writer pen, because it physically cannot put down more than a drop. Use it until the drop is automatic, then use the bottle like I do.
Sold to working automotive professionals for practice and service work. Not a consumer product.