Engine Balancing Problems

I worked as an apprentice in a machine shop.My job? Prep stuff for the machinist. First engine I watched balanced was a Arias 11 to 1 ,stock rotator 340.It took him about 2 hours to dial it in.(After all the piston,pin, and end to end matching.) Just to put it in perspective,my 408 sbm stroker drove him nuts,for about 15 hours.