3 Spoils for 13 hours is extremely low, normally you would expect around 6. to get everything you want you will still need loads of time! i have farmed around 500-600 hours and now i have all WFA-commanders and most of the soviet and wehrmacht ones.
but it seems, that relic wants do do something about duplicates, so they may come in handy at some point!
Yeah, I really didn't expect to get everything I wanted, but I sure did expect more than three spoils! I have looked into duplicates quite a bit, think Cynthia responded to a Steam forum regarding a trading feature in game saying they plan on adding a bit more community suggestions for war spoils, but I think it's been awhile since this was posted. It was around the same time they were doing those surveys, I think.