To answer YOUR question on YOUR rifle, the answer is to know your rifle and ammo. Cleaning frequency depends on many factors, like bullet weight, bullet type, powder charge, hunting conditions, mixing different ammo, etc. If you are running a Barnes TSX at 3000+ fps, cleaning may be every 20 rounds. If you are running a 308 with a 168, it may be 500 rounds. I also do not like mixing different brands/types of ammo on the same cleaning cycle. I have seen several rifles open up after mixing different ammo ( different powder and bullet). So, I'll clean between each ammo type.
Most 6.5 calibers will go 100-200 rounds no problem. My 300 WM needs cleaning after about 70-80 rounds.
Here's some info on cleaning on what I do.
http://texashuntingforum.com/forum/ubbthreads.php/topics/4661544/1/Rifle_Cleaning_for_deer_season