At least twice so far, I've put points in a skill to meet the prerequisite for other skills, and upon meeting that prerequisite, I got a free point in the new "unlocked" skill. Other times, though, I've gotten no free points.
For example, after my alchemist put 5 points in Fire Formula, he did not get a free point in Inferno Formula. Nor did my Gunner get a free point in High Caliber after putting a point in ATK Up. However, my Protector got a free point in Fire Wall, Ice Wall, and Volt Wall after putting her third point in Shield Mastery
Is there a way I can tell which skills I'll get free points in and which I won't?