Glad everyone else runs a tank and flies.Flying circles may have been a bit over the top,most of us will fly mild aerobatics.I was 3Ding on my first flight,just never pushed the motor for any duration.
Most people do not have anywhere to run an engine for hours,without having the neighbors show up with a gun.Our flying site would also not allow such a practice for a long period.Whatever works I guess.
Personally I have never heard of anyone benchtesting or ground break in for 4 hours,especially an overseas throw away engine.But if it makes you feel better and think its the right thing to do,then noone is stopping you.
Happy flying