Not alot of people would agree with this, and this is my suggestion.
I reckon, pasting 99 in a skill. Should entitled you by each million exp you go up, should be an increased chance of a pet.
Say if your 15mil in a skill, 16mil should increase your chances by a couple of %. I know and understand at 200mil its 15% increase by all sources.
But i just feel this would be ideal..
again just a suggestion, some other players may not feel the same way.