>>569993551 event glass is 12 event hours and the early missions give you 3 glass each.
The missions in red can be completed while losing the fight (costs 0 hours) and the one early mission in green still nets 24 event hours (if you didn't scum for it while unlocking the advanced fight).
The advanced battle 5 wins mission probably isn't worth it but every other mission if free stuff at no opportunity cost. 