Hi Willard,
I don't think there is an all in one answer. Depends on your fish, and the frozen food. If you've got more insectivores like maybe rams (?), I don't see why it should be a treat only - it's their natural diet. Bear in mind that they don't only eat one type of creature though so mix it up! They would be targeting this food in the wild rather than flakes! Some fish need more greens, like rainbows, so I'm not sure they would appreciate insect only grub (pun intended) - if you've got veggies, feed them some fresh greens like peas, spinach or courgette - I couldn't believe it when mine went crazy for these! I believe 5 a day is ok (bad joke)
I've also read loads of threads of people not trusting frozen blood worm and. quite a few people have lost fish shortly after feeding them. I've not had this myself but its made me think twice about using them - the live version is also far more fun!
I can't remember who it is, but one of the mods or at least very regular posters, has a tank where he adds loads of micro fauna to it, basically there are loads of wild micro organisms for his fish to feed on- sounds like the ultimate tank to me.
Most prepared fish food is like us eating ready meals all the time, nature is far better at getting things right! have a read up on micro worm cultures and breeding your own daphnia, I reckon this is the fish version of heston blumental!