I stay around 25 to 50%, depending on the color I'm spraying, how the prep work was done or how much of a solvent barrier I want the epoxy to be. I hope the more experienced painters will explain it better than me.
Epoxy as a sealer can have different uses.
Today I sprayed some small pieces of MDF and I probably reduced the epoxy 25/30 % didn't even measure it properly. Shot a single coat, let it seat for 45 mins then used the 2K gray sealer with Polar accelerator as a primer. Was sanding within an hour, broke through the edges then I resealed it with the previous mixed epoxy, waited 20 mins and base and clear.
Worked very well.