I have not had a patch come out in the same condition as it went in (clean no marks)
I use VFG felts on my barrels, only use a pull through when the barrel is very dirty.
End of the days shooting, pop a felt in and fire it into a small towel. Look at the felt and see how much lead it has picked up on the way through. If it is completey black all the way round, I shoot a few more through. When I can see just the lands ( looks like spirals on the felt) I stop. If I'm not going to use the rifle for a while, I will put a drop of LT1 on the last felt, fire it through and pack up the rifle.
Only when my aim points are going off, do I use a pull through.