the bogmaster is right...single handled one for rats, maybe small mink, but everything else I use a two-handled one for. Type of fleshing tool (there are many on the market) is one factor, type of beam you are using...the beam must match the catch and blade both, and then rest is just learning technique to apply when using one.
A coon hide for example, is tough on the back side, especially in the neck region, but the sides and bellies are much softer.
A possum hide is incredibly thin and tears easily, as do fox and cats. Prime coyotes are tough, but they have their tender areas too. Using more of a "push" than a cutting action in some cases works better. Too agressive on beaver and you start tearing out guard hairs...but beaver gristle and fat can really be a chore. Its all about technique. I had to ruin a few hides to get it down myself.