For an adult dragon 3-5 superworms a day is a little too much as they can be rather fatty. Adults also don't need insects every day. Offering that many a day only a couple times a week would be better. However if he's not showing any sighs of putting on alot of fat (ie fatty areas behind arms, chin, base of tail etc) and is very active, it may be fine but I would still recommend cutting back to offering only a few times a week.
I am not sure how long it takes for a superworm to complete their larva stage and pupate into an adult beetle, however I have hard that if your dragon will eat them dead, you can just freeze them, then thaw to offer as a treat. I haven't personally tried this and the guy who mentioned it to me was from a local petstore who's employees or owners know all that much about the animals they torture..err I mean sell, so I am reluctant to take his suggestion as a good one. For all I know freezing and thawing a superworm may wind up leaving me with a discusting mass of husks and goo.