Hell the way I ride I would need a colostomy bag hooked up to my bike. My changes are 5000 syn oil, 10000 all holes. Seems to work good for me last bike 09 streetglide 58000 no problems new bike 14 streetglide maybe two weeks all 3 holes 10000 miles. If I used reg oil maybe every 3k but not all 3 holes over kill.
I don't see the necessity of changing the transmission/primary every 3K. The crankcase is a totally different matter and depends on how u ride and the conditions.
I change the all the oils every day, cheap insurance. Full synthetic oil of course. Nothing is too good for my baby. New tires every month and new pistons and rings every fall, can't be too careful!!!!