The mechanic is counterintuitive and not described anywhere.
Based on research done by people in this reddit thread:
link
The formula for skill learning rate is:
LearningRate = 20 / ( 10 + HeroLevel) * (1 + 0.4 * Attribute + Focus)
The first part
20 / ( 10 + HeroLevel) is presented as "Base" in skill learning tooltip, and it acts as multiplier to the whole learning rate.
It means that:
- hero at level 10 will have (base 1.00) and will get xp -45% slower than hero at level 1 (base 1.82)
- hero at level 20 will have (base 0.66) and will get xp another -33% slower than at level 10 (base 1.00).
The counterintuitive thing is that it scales down with character level, which means character gaining skill levels in one skill, enough to level up, causes his learning rate to drop for all skills. It is counterintuitive, because player may want to level up easier skills to accumulate attribute points and focus points, so then he can learn some harder skill at increased rate. But with current formula before he accumulates these points, his learning rate will already drop from just leveling itself. Which to be honest has demotivated me quite a lot when I learned about it...
I understand that player progression should be harder for high level characters but for that, we already have skill learning rate getting lower the closer you are to learning limits, and also xp required for each level getting higher with each level. Having learning rate of skill you didn't even use yet, drop with your character level, it just as counterintuitive as it could be.
And because every good thread deserves screenshots:
Here is my character at level 1 and level 7:
As you see the learning rate of Smithing, the skill I didn't even use yet on this character, dropped from 4.00 to 2.59 (which is -35%), simply because my character leveled from level 1 to level 7 by fighting looters... Very demotivating...