Buck 89: Might depend somewhat on the bullets used. I have one of my original 1-14 twist 6 BR's, Shilen heavy contour, straight taper, now with a documented 1750 rds. fired, with a steady diet of nothing but 68 gr. Bergers, #24411. As seen with my Hawkeye, the throat is close to being in the same condition it was as when new. Bullet seating depth has changed very little to touch the lands. It still holds the same accuracy level (very) as when new. Standard powder charge has always been 30 grs. of N133.
At the other end, I recently had to pull a Hart ( also button cut, like the Shilen), also a heavy contour, straight taper 1-8 twist after 2000 rds. fired. It started to throw an occassional uncalled wild shot, began to copper foul, and I'm seeing a good bit of erosion in the throat with firecracking. It had nothing but 30 grs. of Varget with the 107 SMK's. Bullet seating depth increased to where the bullet would no longer touch the lands & maintain acceptable bullet/case neck contact.
So, based on those two comparisons you could say "over 2000 with shorter, lightweight bullets, and in this example a milder powder charge, not at maximum". "Around 2000 rounds if a fast twist with long, heavyweight bullets & a near maximum powder charge".
Just trying to breakdown the response using these two examples, not based on "I think".
As dreever said, the answer also depends "on your expectations". Some would be happy with moa 3 shot group sizes. Others demand 1/2 or 1/4 moa average groups, and the ability to have faith in it in a match.
ps: At the extreme, I know a guy who blasts away with an AR-15 with well over 20,000 rds. fired (I'm not joking), gets 8" "groups" at 100 yds., with most of the bullets keyholing, but he considers the rifle to be "accurate", since he can hit a paper pie plate. ;D