If you are at the ragged edge and take one step ............... So yes, one size jet too small may make the difference, or if you are near lean at say 85* and 90% humidity and tomorrow it's 70* and 40% ...................
As you lean an engine power increases as does temperatures, as you go lean from "perfect", power doesn't drop as fast as it rose from rich, BUT temps rise dramatically leading to deto or melt down.
My school of thought is that plugs are cheaper than pistons, somebody is always faster, and if I leave a horse or two in the barn so be it. My name is John, but my last is not Force