If you dont follow PTS subforum, here is a thing, as
@Asayre found out (and later other people joined in), starting from Morrowind almost every CP star will use so called "jump points" (before it was limited only to two CP stars). What does it mean? Even if we can distribute 100CP into specific star, it might happen that even if adding 5CP promises us X.X% of increase(decrease) of something, it wont happen because we did not reach next "jump point".
https://forums.elderscrollsonline.com/en/discussion/340367/impact-of-mage-champion-point-rebalances/p1
Taken from that thread, for a CP star that max out at 15% the jump points are at 0, 4, 7,11,15,19,23,27,32,37,43,49,56,64,75,100 CP's.
This practically means that if you are currently at 4CP in that tree and you want to add more CP in there, if you wont reach next jump point (at 7CP) all the new CP are wasted.
Other example is that if you are at 75CP, all the CP added in there, untill you reach 100CP, do not give you any benefit (beside generic slight increase to max resources). If its a "Reduce damage taken" CP passive, the damage you take will be exactly same at 75CP as at 99CP (despite that in between these points, CP passive tooltip is suggesting that you should notice difference).
Whoever wants to learn more about this, please visit mentioned thread while we go back to the point. And what is the point? Just like with many other things, players are not told about this anywhere. If nobody would discover it players would invest CP, expecting X.X% change in stats (as its promised by CP tooltip) while they are getting nothing.
Despite these jump points being in game, players are still told in CP toltips that adding 1CP will give them increase/decrease to stat while in most extreme cases they would need to add whole 24CP for a change to happen.
The sole existence of "jump points" aside, I personally thing that worst thing about it is that players are not properly informed about it. Why tell us we will get 0.5% increase of something if its not true? Why not make it show real numbers as "next increase at X CP"?