you can get prty decent power while saving as well... focus for example on getting moon and sun scrolls and buy cave keys enough for rebates and assist potions and buy refines and charms, you can get a command flag for free every few weeks just by collecting the packs with free points you are doing, as i said there are ways to improve/gain power without spending...

if you dont want or cant go for fuku there are some events that i personally see them worth spending a little such as 3.5k cp in great plates cuz it gives skill trial matherials and do enough to get the 500 reward, fuku shop is worth checking in if you get a 50% coupon since it applies per stack of what you buy, things like wheels and stuff are sort of scams since is waay too much rng, so my advice never go for a ninja on a wheel

my toughs on fuku alone, nowadays is sort of 50-50, some time ago fuku was kinda guarantee to be good, if the ninja wasnt good at least the power packs was good (hell at one point we had power packs fuku only) so, it might be very very good investment of sort of bad one HOWEVER don't forget when you spend coupons on fuku, those coupons dont just vanish.. you spend them in events thus you get ninjas/power from those events on top of fuku rewards, thats why beside the hope for a good fuku there is the hope of a good event cycle for said fuku (for example konoha tree since beside the things you buy with points it drops certain things while drawing) , lucky star sometimes might be good as well depending on whats on the wheel, but if you go on lucky star dont roll for the ninja that is on the wheel, go for a point reward from it, if it happens to get the ninja reward thats a bonus

hope makes sense any of what i wrote