I always check the gap on every ring, file the top and second to fit and then slide the two oil rings in and check them with a feeler gauge to make sure they have the minimum recommended by the ring manufacturer
As far as spacing the rings I use the 1/3 or 1/2 the way around method, set the bottom oil ring gap at close to 4 o clock looking down into the cylinder, set the second gap at or close to 9 or 10 o clock and then the middle ring gap at 3 o clock and the top ring gap at 8, 9 or 10 o clock, your choice
I have check motors that I set the ring gaps on and mark them down on motors that I knew I would take apart before turning them over to the customer Them dang gaps, usually, don't stay put, they moved all over the place every time I checked them
Other engine builders have told me the same thing on the ones they checked
that really suprised me
especially on the oil rings
I hope this helps