It is always best to take advice from a petstore employee with a grain of salt and do your own research instead, like you are doing. Sadly the employees at most stores are very poorly educated on proper betta care.
They likely use this feeding routine for their bettas in those tiny cups to help reduce the amount of waste and therefore buildup of ammonia so they can use that excuse not to change the water very often(which is just plain horrible if you ask me, even temporarily). However, as a regular feeding schedule, this would leave a betta extremely malnourished and underfed. After you get the Omega One, you should offer him 2-3 pellets twice per day and you can offer frozen foods like Bloodworms, Brine Shrimp, and/or Krill as treats for a little variety/more balanced diet replacing a meal a couple of times per week. You can offer freeze-dried foods as well/instead, but frozen is a little better.