Personally I wouldn't stick to anything unless who ever told me the info. can give me a reason...but that's just me.
Most people say to limit mealworms because they are fatty and not a substantial source of protein. They also say they will fill up on the mealies and not eat their staple.
I can promise you,...my gliders are just fine and they eat more than 6 mealies a day.
And they always eat all of their dinner.
As far as other worms...I have never offered snails. I have offered silk worms and my gliders wouldn't eat them. They seemed to be bitter...
The one glider I have that attempted to eat the silk worms would bite, then shake his head like he bit into something not so great. And none of them liked to hold them. They would shake their paws like a cat that stepped in water. I think because they are "sticky" the gliders didn't like the feel of them. But if yours decide they like them, if it were me, I'd only give one or two...they are quite a bit bigger than mealies and I would imagine one would fill a tiny glider tummy in no time.
Other than that I think there is a place, maybe even on here where you can look up the nutritional value of insects. That may help answer your questions as to how many to feed.