Is it level based then? No stat increases the amount of skill points you gain per level? I understand the multiplier just not what governs the base number you get before it's multiplied by 1.0 or 0.8 and so on.
No stat increase skill gained, skill gained is the same roll each time multiplied by the bonuses from each races/classes
OTOH, it seems one of mental stats does affect skill gain rate for some skills that develop with use. When I was grinding climbing, my spellcasters used every climb to raise the skill, quickly maxing it. The less intellectually developed dwarven berserker and wolfin ranger were at around 50 by that moment, and it took them twice as many attempts to max it. By the time they did, my dumb as a brick saurian was under 40, I spent 3 times as much time grinding him alone, and gave up at about 80. He only increased in, like, 1 out of 8 climbs.
Curiously, this is not true for swimming, everyone learns it at equal rate and finishes simultaneously.