850 coupon used on Sn4tch i gt none 100 coupons but atleast i gt Minato and a lot of charms and magatamas lvl 5 . so good investment to increase my power

I won't burn resource on pure RNG events like that as what you said can happen, it's a meh event.

However, where is your data. And did you collect data in collaboration with others or did you burn 50k coupon/ingot on it yourself?

Do note that you need to avoid self-selection bias in your data collection. Intend, participation and methodology must be established before the actual collection process.

im going off the 3 servers i play on and a average i have seen the anouncement once since event came out , compared to several times perday before hand

To make this event appealing they should remove everything that's less worth than 50 coupons or that is worth it but none would ever spend coupons to get them, or they should add other steps before the 50 goal (for 5, 10, 25 for example) or they should cut the cost for 1 roll to 20/25 coupons and add 1 free roll per day. (The great plates event was WAY better than this event, but was removed and never showed again just because people didn't like it).

investing 50 coupons or 498 for 10 tries (meh...) is not a little thing for a f2p or for a low cashing player, to do it on a board where out of 14 slots 2 of them are less worth than 50 coupons (2 seal scroll fragments, 20 coupons), other 3 are worth it but wholly out of any purchasing intention any not out of mind person could have (stamina potion, summon scroll, 3 purification protection runes) and other 4 are subpar or very not useful after the first 2-3 times you get them in your whole playing life time (tendo fragment, summon contract scroll for the not useful part and 5 unbound runes packet and 5 cave keys for the subpar part) doesn't seem that appealing.

The fact that are there 100 coupons, 1 charm pack, 1 magatama level 5 pack, 30 kushina fragments and 80 minato fragments as the other 5 slots doesn't induce them in any way in trying more than once per event to see if they are lucky (overall knowing or reasonable thinking that all of the good rewards have not at all an 1/14 chance to be rolled out).

The only good thing i see in this sna(tch) is that they finally put it not together with lucky board, but still not worth more than 1 try per week imho.

i spent 2500 coupons and dont get minato XD, i shoud have use it to buy cloth XD, silly me, but its very tempting dont u think?

This is just my thought. I think it is just like konoha tree and this along with the time limited shop would help the big spenders to get naruto nine tails chakra fragments. For normally putting coupons it doesnt break even because the redeem points are too far away as Garv mentioned. Also the drop rates of stamina potion and the blocks with less than 50 coupon value are too high. I dont have proper statistics of this, but I was not ready to go get it after my first 10 draws turned out to be a disaster. Probably they should work on these drop rates to make it more profitable event. One thing i have noticed is first draw has a high chance of being a good reward.

But that only says something about the output, it says nothing about the input. How do you know the input haven't dropped (because people figured out that it's bad and/or because the big ptw who would go for it already have the ninja)

That's just not an acceptable testing methodology/data collection.