Tile etching - How much paint is too much paint? Is paint the way to go?

In this video, I am using my LE5040 Genmistu laser. It has a 5.5 watt, variable focus laser at the time of this video.
In all of the white tiles I have painted and etched, I never remember taking the time to experiment, at the same time, with how much paint to put on a tile. We found with the Cold Galvanizing Compound that it was easy to put too much on.
I have had people ask me about issues they are having with this process where you paint a tile with white paint and then burn it with your laser. Where you burn it, the white paint turns black and sticks to the tile. It is a fun project and doesn't cost too much either.
I have had hit and miss issues over the years and there are three things that make this work or fail. Focus, speed and power, and amount of paint. All of these things have to be correct or your burn will fail or not be as good as you want.
It is easy to put too much paint on the tile and your burn parameters will be wrong. When I am going to be doing tiles, I try to paint up 8 to 12 or more at the same time so they are as close to being the same as I can get them. Focus, focus, focus! If your laser is out of focus, it won't burn how you need/want.
In light burn, it is easy to run a material test to determine where you sweet spots are for burn speed and power. The amount of paint you put on the tile will greatly affect these numbers so keep consistent on applying the paint.