I ran a 1/2 tank thru my gas 52cc motor,it ran fine,good enough to fly lazy circuits.So I topped it up and went flying,done.
Most guys just rough tune and fly gently to break in.Running a gasser for 2 hours on the ground sounds absolutely ridicilous,somewhat frightening really.Mine was also not a DL,but still.
I do the same with glow motors too,as soon as they seem reliable at idle and transition they get to go fly.I take it easy,short bursts of power,shallow climbs,and low throttle circuits.Glow motors were a bit rich to start,gassers were tuned,close to max rpm,but not rich and then flown.Has worked for over 20 years and 15 engines.