When I last painted, we would paint, dry with heat lamps and outside once the top layer was hard, then colorsand, and compound new paint, and then apply Meguiars Nbr7 Show Car Glaze to it..
The Meguiars Glaze would not seal in the paint and would actually come off easily by the next wash or heavy rain...
I still believe today, that as long as you can smell the paint fumes coming from the paintwork, it is still curing from the bottom layer up to the top and gone..
Notice how when you purchase a new car from the Dealership - they never smell like new paint???
They have dried them in heat and then the cars sat outside for months in the sun curing even more...
So, hope this helps answer your question..
Dan F