No gap. I’m using a multi-meter, roping the motor around watching for the points to break continuity,
The manual goes through the process, but doesn’t specify which set to start with. As you say, I set the ones which broke when the marks aligned, not the ones which were at a / the high point. My fumbling suggested it’s not possible to get them adjusted correctly, if you start with the wrong set. Even if you try for hours, in the sun.
I tried using a feeler gauge at first, but that never worked for me. I think, after years, I figured out why. The cam lobe isn’t really rectangular. Two of the corners are the “high points”, and two are lower. A bit slow I am, but have found roping it around to work well. I set the feeler gauge down a while back.