Starting with the first tank of gas.

There's absolutely no reason to run common high carbon oil in an engine. If you feel the need to break the ring in as fast as physically possible just toss some sand in the engine Makes about as much sense as using a lower quality oil than what you can obtain for the same price in high quality.

The ring is not the critical item, it's the thermal cycling. Doing it right and not scraping it down in the first few runs matters, but it's not the most important break in factor. The cylinder lining is a lot harder than the ring and doesn't really wear. If it did the cylinders would have to be tossed at 50 hours or so since the chrome plating is so thin. Oil has no impact on the thermal cycling unless you don't use enough of it. Then any engine will get frictionally hot , ending it's useful life regardless of oil type.

Three running hours is three running hours for a good break in. The number of gallons it takes to get there doesn't matter.