Once I found this and was able to play around I found out I had wasted a few skill points here and there, especially once you learn the mechanics of how the skill tree works. For instance, you don't need to buy a skill in each level. You just need to spend skill points to unlock the other tiers. So it can work out that you might ace two skills on one tier and then unlock two tiers higher (as an example).
Once I played around I found out I was able to get some basic skills in master mind that make stealth a lot easier. And I should still have plenty of points to get some boss turrets for go loud style missions.