it took me 3 months total to save up 20k (but i'm not really f2p). if i just take the f2p parts into consideration, i make slightly over 1k in a week. i made a detailed spreadsheet to help me track expenses when i was saving for 20k. my main sources of coupons:

- convoy/plunder

- group wheel (i defaulted this at 10 coupons a day to make room for rng)

- group summon

- friendship tree

- daily 1hr login

- myoboku trial/wishing lantern

- ninja puzzle

- monthly login

convoy doesnt take much effort. get yourself a daily checklist so you don't miss out on important things like this. even in the midst of my exams i managed to take a 5 minute break to complete convoys and plunder.

i imagine if you're determined to save up 20k coupons, you're determined enough not to forget convoy.

btw i checked my spreadsheet, you can reliably get 1.2k coupons a week if you complete the list of tasks i gave in my previous post. granted you'll miss out on cave keys from the wishing tree, but if you're doing 3v3 and dailies regularly, you should still be able to hit 1k50 keys a month as i did.

1. ninja puzzle comes and goes, but we're talking about on average. that means it doesnt need to be there every week. from personal experience, it comes about once every 2 weeks. I put this down in my spreadsheet just for logistic purposes since it is still a source of coupons. it still adds to the overall total of the coupons and is a necessary component.

2. lol then you just gotta deal with it and adjust accordingly

3. even by claiming coupons from the wishing tree, you should still be able to reach 1050 keys per month (as i have already mentioned in a previous post). I'm speaking, repeatedly, from personal experience. Even if you level freeze. Yes, it is a loss of value. No, it will not affect you drastically. No, you don't have to keep claiming coupons from the wishing tree after you've achieved 20k coupons. This is the way i managed to ac*ulate 20k as fast as possible.

if you wanted dither and quibble about small amounts of value loss you wouldnt bother rushing to save 20k anyway.

you lose huge amounts of both power and value when you're going for huge goals like this, and as time goes on, the power loss is a much larger concern that the loss of value. you can fall behind by as much as 15-20k bp during the time you're saving up and it's more important to minimizes this than value loss