Before there were corn cobs (they only showed up after the Europeans rediscovered America), there were leaves and, yes, fingers. Santitation was not too good in Europe and understanding of what was "dirty" was not all that clear. The Arabs only used their left hands for that purpose and ate with their right hands.
Lots of water, as Jack said, is a good thing. For years now I have been trying to figure just how much water to use backflushing, but that depends how much water pressure there is. I could run inside and check the tank monitor, but it is usually wrong, why bother? I suppose there is an inline meter available to tell me how much water passes through the backflush hose, but that seems like getting into OCD territory. If there is high pressure and I backflush for 4 minutes, I may have a waterfall down the side of the trailer—the water will back up the soil stack (vent) and down the side (it does test the toilet flapper seal to see if it is watertight). This is the kind of thing that causes you to first look around to see if anyone noticed, then you turn off the water.
I find that 2-2 1/2 minutes will get plenty of water in the tank, but 30 seconds will get a lot of stuff out too. I may start with 2 minutes and then do it for 30 seconds several times and finish with another 2 minutes to get clear water.
It takes a long time to fill the black tank (less if you put dishwater in it), but generally it starts to smell bad at about a week and no amount of tank deodorant and keeping the bathroom fan on all the time will help much. Until either odor time arrives or we are going home, we never open the black tank valve—that asks for solidifying of whatever doesn't float out right away and eventually a black tank with lots of hard nasty stuff in it (and a fork).
With plenty of water, whether or not toilet paper dissolves doesn't seem to matter. After all, the "solids" do not always dissolves either.