Barrels can be very different.
Some needs a bit of fouling, others not at all.
Some are very smooth and gets hardly any fouling at all.
Others needs a cleaning after few shots as it fouls very quickly.
And they can all very very accurate when they get the situation they need.
And some seems to not care much about what they get, they are either always accurate or never accurate at all.
I owned a 9.3x62 Mauser with a S&L barrel that was very finicky.
It always needed 2-3 fouling shots and then it was very accurate( 1/2 moa 3 shot groups) for 20-25 more shots and then the accuracy deteriorated quickly.
I hate gun cleaning, so I sold it to a friend that likes to clean his guns.
My 6.5-06 with a Shilen stainless steel barrel is very smooth and hardly needs any cleaning at all.
I have had it for 22 years now and I think I have cleaned it 3 times in that time and shot around 3500-4000 shots with it.
And it shoots sub 1/2 moa 3 shot groups with my best loads, 1 moa groups with almost whatever I feed it with and most loads hit the same spot at 100 meters.
My 80 gr Norma FMJ RN, 85 gr Sierra Varmint, 100 gr Sierra Varmint, 120 gr Swift A-frame and 120 gr TTSX loads make a sub 1" group at 100 meters.
My Tikka M65 in 6.5x55 is also very accurate and doesn't need much cleaning.
I don't know how many thousands of shots that have gone through the barrel as I bought it used and the previous owner had used it for competition shooting.
I don't know if he ever cleaned the gun as the barrel was extremely fouled when I bought it.
But when I finally got it totally clean, it shot very well.
I have still not cleaned it again after that first time and even after minimum 1000 more shots, it still is very accurate.
I have managed to ruin one barrel because of lack of cleaning.
Or to be correct. Because of lack of getting the barrel dry and leaving the silencer on.
I had been out hunting with my 223 Remington 7 with a silencer in very bad weather conditions and shot a deer.
When I came home, I had to rush off and had no time to clean the gun and just put it in the gun safe and totally forgot about removing the silencer because of the stress.
Of course I managed to totally forget about the gun in the safe for some months
, even if I took other guns from the safe and hunted with them.
When I took the gun to the shooting range, I had 10" groups at 100 meter if I was lucky
The barrel was totally ruined with one of the sides in the barrel at the muzzle being almost like a smooth bore
I felt like a total idiot then
It has not made me clean my guns more, but I make very sure to take the silencer off of the guns that have them when I come home from a hunt.