Texas chip insurance limiting supplies

Hi my daughter was diagnosed Novemeber 2017 at the age of 6 she had health coverage thru texas chip under the community health choice health plan. We have always had trouble with getting her prescriptions filled for the month supply. She gets all her prescritpitons split in half so we go to Walgreens twice a month to get her months worth of strips insulin etc because they tell us insurance doesnt allow them to give us the moth supply all at once. I talked to my daughters Endo Doctor and she said thats how some insurances work. So my question is if this is true ? I basically make 2 copayments each for all her prescriptions to be filled for the month at walgreens. This year i switched plans thinking that was the problem and im still having the same issues i now have texas childrens health plan thru chip .