Mostly the fouling was more or less ignored by using a much smaller ball than bore diameter. Most paper cartridges used by the military had a o.690" ball wrapped in the paper cartridge in the 0.770" bore of a Land Pattern musket. In situations such as that there would often be time between volleys to run a damp wad of tow up and down the barrel to remove enough fouling to keep on firing. The heat from the previous firing would dry the bore before the next load was presented.
In most line of battle situations, the practice was three shots and a bayonet charge.
In a siege or treed up stand off, there was time enough to run a spit lubricated wad of tow down the barrel to remove enough fouling to continue firing.
When the unit participates in woods walks and we are firing live ammunition, the ball is usually 0.715" in a paper wrapped cartridge. The paper is not lubricated. I have learned and tried to explain to the members of the team to spit on the ball end of the cartridge so when we are in the rapid fire situation where we need to get off 5 or 6 shots in succession. If the ball is not dampened in its paper wrapping the ball will be hard to load. In one stake breaking shoot, several members had balls get stuck in the bore. It required a quick sip from the canteen and spit down the bore along with the steady support of a nearby tree to seat the ball on the powder.
We are not, in most situations, in a line of battle situation. We have the opportunity to look at other methods to control fouling. In some shooting conditions or competitions, I will have a 0.735" ball (paper wrapped) to load down my 0.770" bore. I also will have enough time after the second shot to run my tow (dampened of course) down the barrel. The ball of tow has a linen string tied to the ball of tow to aid in removal of the tow. After the shooting, I rinse the tow and it is good to use for the next series of shots. I do have the steel ram rod to use in competition.