I find that giving a ration of seed in the morning and one in the evening works well.
The pellets are left in the cage 24/7 so the budgies have those to eat throughout the day.
I do not fill the food dish however, I only put a Tablespoon or so of pellets in the dish.
I leave the pellets in the cage until they are eaten or crumbled into powder.
Then I dispose of the residue (for the outside birds) and put fresh pellets in the dish.
I don't freeze the pellets, I simply keep them in airtight containers.
When I introduced pellets to my budgie, my Avian Vet recommended using Harrison's High Potency Mash and sprinkling it on the budgie's seed mix every day.
This way, when the budgie hulls the seed it tastes the pellet mash and ingests bits of it as well.
This helps the budgie identify the taste as a food source.