Theory is great, and there is plenty of it on this topic. I try not to let it swollow up the objective - and that would be to keep the combustion chamber pressure / mix in the combustion chamber. I realize there are always trade offs, but any leakage past the first or second ring ( no matter how it occurs ) can only read negative. One of those built in leaks is ring end gap. So,IMO, you set the end gaps as tight as you can, leaving clearance for heat expansion and - a "safety margin" per my example. My piston manufacturer called for .030" top ring end gap. I set them at .032". Second ring went in at .016". I have had several overheat situations since with no ill effects.