You have a misunderstanding... a 1 edo hashi per 40 pulls is a figure to show you that you are getting 1 or 2 frags per 60 pulls which means an average of 1.5 frags each 60 pulls which is equal to 1 each 40 pulls... so edo hashi will be recruited at 3k scrolls in normal cases .. but here is the scenarios if you pull during rebates

800 pulls rebate:-

you need only 734 seal scrolls getting 66 free scrolls from rebate

So 734 which is by rebate =800 so each 734 pulls will give you 800/40=20 frags+5 frags rebate

Assume 5 frags will be pulled in free pulls so you need 75 frags

then 75 need 3 rebates of 800 pulls which is actually 734 then you will need 734*3=2202 pulls

300 pulls rebate:-

you need only 264 seal scrolls getting 36 free scrolls from rebate and then after the 300 pull you will get extra 30.

So 264 which is by rebate =330 so each 264 pulls will give you 330/40=8.25 frags

and since we assumed that you will get 5 frags in free pulls so you need 75 frags so 75/8.25= you will need 9.1 rebate of 264 scrolls which is = 2400 pulls also.

So 2400 pulls+200 free pulls= 2600 pulls will give edo hashi in rebates of 300 and 2202+200 free pulls =2402 in rebates of 800.

Last advice, if you got both your super rares in GNW treasures before reaching edo hashirama then ou should go for edo jins treasures to get new ninjas and edo hashi fragments.

this is based on so many pulls from different servers.. it may vary ofc.. but after lots of pulls you will find the rate as I have mentioned