All else being equal, same race, same class, same stats (and we'll assume morale is the same) can two separate characters learn at completely different rates?

I know there is always the luck stat you can't see that probably plays a part and of course you're always reliant on the RNG, but it seems I've played 24 and 25 int characters with decent morale that just don't learn quickly at all.

The reason I ask it is to try and determine whether it's worth it to stick it out, or if it would save time in the end to just reroll and start over.

For that matter, I always have some hesitations with a high int character who makes it to level 5 or 6 without a single skill improvement.

Thoughts?