Enriched or fortified foods are fine. Most regular brine in stores is void of any real nutrition. It's like giving candy to kids, they'll eat it all day and get nothing from it. It is also low in usable protein. Mysis shrimp is much better if you feel the need to feed meaty foods.
Personally I only feed fortified flakes on a regular basis. A few different types alternating each on different days. A meat style flake and spurlina. It is very healthy for the fish, will not promote intestinal ailments like frozen meats and will also not pollute the tank as easily.,
What you are doing now is fine, just not my preference...