Skill XP calculation

I saw this formula someone posted in the forum but I can't vouch for it's accuracy.

Formula to calculate Skill XP:
(Taken from here, credit goes to ToonXW)

For punching, one can gain 3 Sword/Magic points. Adept will not affect the overall experience gained from punching or using normal attacks.

Casting an attack skill:
"Cast time of skills" * 12 = gained Skill XP

Casting a buff skill:
"Cast time of buff" * 3,6 = gained Skill XP
3 for some buffs and 6 for others.

Adept items just adds to the skill xp. Maximum bonus skill exp is 36. The maximum skill exp you may gain from adept is therefore 36.

Example:

Force Archer Skill "Power Shot" at level 9
Casting time: 1.3 Sec.
Used equipment:
Board +4
Citrine Crystals +8
Adept Rings + Amulet (Level 80 Items) +20
Adept Aramid Battle Suit +4
(all in all +36 Skill XP)

Calculating:
"Casting time" * 12 = 15.6
15.6 + "Skill XP Items" (36 Skill XP) = 51.6 Skill XP