This kinda thinking can really get you in trouble. Behold the awesome power of my highest level ninja:
See, here's the thing about niche units: they're fucking
niche. Oh, they have their uses, sure, but those uses do not come up with every event, and since 2-3 events a month is what qualifies as a relatively busy schedule here on Nutaku that means that realistically the lack of a high quality Nagi substitute is likely cost you less than half dozen SC a year due to missing out on 3 star clears. That sort of missed opportunity is a drop of piss in the ocean compared to falling behind on your core units. This Nagi event isn't a complete waste of time since the 100/2 map is so efficient and you get some rewards on the side as well, but seriously, if you're suffering as much as some of your posts have implied than I really would consider doing the Monday & Thursday dailies like normal.