XP Overflow
Level 7 soldiers tend to do the bulk of the heavy-lifting and, despite having no use for it, take the lion’s share of a mission’s available XP. This mod aims to rectify the amount of XP that gets wasted on LV7 soldiers by converting their unused XP to additional Skillpoints. These Skillpoints can be assigned to the soldier’s pool or the common (Phoenix) pool.
In fact, despite talking about the XP wastage of LV7 soldiers, you can allow the SP trickle to occur for all soldiers regardless of their level: This mod is highly configurable so that you can adjust the balance as you see fit!
GitHub link for Source code and PPME (non-Steam user) release[github.com]
There are a couple of older mods on Nexus that implement this overflow mechanic for LV7 soldiers, originally in ElleSheepy’s "Spill Exp to Skill" and later in Mad’s "Assorted Adjustments". While my code differs a fair amount from theirs, I take no credit for the idea: I merely ported this feature to the Steam Workshop and improved its configurability.