Some conferences are requiring the COA stipend go to all athletes. I don’t think there is an requirement that it be in proportion to the scholarship. Perhaps an athletic director could say every athlete gets $1000 rather than some getting $2000 and some getting $100. The easiest way would seem to be to get the stipends in proportion to the percentage of scholarships.
I do think at the beginning they were all thinking that everyone would get the full stipend. When the real numbers came out that it would cost $1m to give the stipends to everyone, then the idea of a percentage came in.