at 5" they do not require multiple feeding, depends on how much current flow you have in your tank, you can do 2 to 3 times a week, unless pygo, serra will usually stop eating once they are full so they won't get too fat too fast but if there's not much current in the tank you will want to reduce the feeding a bit since it's not getting enough exercise. personally i rather have the fish with a health lean body than an obese fat body just trying to get a little extra growth out of the fish.
keep your water clean will benefit better on the growth than trying to power feed it.