All I know for sure is that if I spend 720 stam on 80 maps I get more lvl 100 dragons than spending 750 stam on 50 maps.

I did test that a few times when I was needing all colour drags and since then I just go with 80s.

Also as a note... I have never seen a lvl 100 drag from the 25 maps, not saying it cannot happen but I have not seen it.