Description: when assigning leaders to fleets they appear to gain experience and levels absurdly slowly, especially compared to those on systems. I can go through multiple combats with a leader - with multiple ships - and not gain a single level. I've had leaders on fleets for 50 turns and they don't gain a single level unless they start with the +4/6 exp stat boost. 

Perhaps this is a Riftborn thing? If so, it is unclear from the game text that this is the case.

Reproducibility: 5/5. Combat doesn't give much experience, as an example.

Suggestion: make combats (especially early ones) accelerate greatly leader experience. Possibly exploring too.