As Mr. Carlson says above, first and foremost the cylinder must be prepared to a high quality state.
The piston ring has an important job to preform in only milliseconds. The ring ends gap is not only there to provide enough clearance to avoid butting. The ring ends gap contributes to the gas pressure entering the ring land and pressurizing the area behind the ring to help seal it to the cylinder wall. Ring spring tension alone can not hold back cylinder pressure during the power phase.
There are many factors affecting your end gap decision.
For few examples: a freshly bored and honed steel cylinder with 280 grit Sunnen stones and an out of the box new ring, can be set up very tight. Because on initial break-in this ring is designed to "seat in" (ware) as is the 280 grit cylinder. This is proper and correct but takes some time to "come in".
The same scenario exactly with a cool bore. Only the aluminum cylinder will "come in" sooner,,, glaze.
Now with a healthy used cylinder or freshly fine plateau honed cylinder and a fine finished ground face ring, the gap will have to be set up a few thousandths looser. Because there will not be as much "ware in" at initial start up. Steel or Cool bore these will "come in" very soon.
A note here,, IMHO a good healthy "Used" cylinder with a fine finished ground ring is the best we can ask for. IMHO if the cylinder is not to be bored don't touch it ! Don't break the glaze, grow the glaze. Just think, how many laps does it take to equal a season of mowing lawns ?
Best, WP