Lets do the calculation for 1 month.

8 come from monthly event.

10-15 come from matsuri (getting a very minimum of 4 wins with almost always 5 wins is not that hard after a certain BP point).

10-15 come from survival/sealed (if you do not get at least 2-3 per week from sealed or survival trial something is off).

10 come from weekend activity (the weekend activity usually grant 1-3 seal scrolls in average per week).

3-4 come from swb and jinchuriki rescue (even if you are not able to be top3 around 30% of the times you are in the winning side in swb + 4 fragments per week from jinchuriki rescue).

2-4 come from ninja fragment refinement (you gather around 300 points per day there even if you do not actually go fully for it. Are 9k a month that means 2-6 seals from iruka refinement).

6 come from arena.

Just from those things we get 50-60.

Add 30-50 from gnw and you are at the 80-100 tier.

Beware that this is without considering ninja test (once in a while gives 1 seal scroll as result), treasure hunt (5 seal fragments are common), space time and the whole weekly events that usually in a month grant another 10-15 seals.

If you consider them in + the seals you get from the rebate every time you reach 184-200 or 264-300 scrolls gathered and you got the 120-150 tier i talked about.

EDIT: i drew last time in gnw treasure on the 28th of may.

so i'm at 89 seals. 20 of them are from the rebate (just hit the 200 mark and i owned only 184, couldn't wait to draw in it because i was close to super rare).

So i gained 69 in 19 days. It's an average of 110 for this month without considering the rebate and the fact last 3 weeks i got only elite packs in gnw because i'm a too kind leader. Add both of them in and you got that what i gained is in line with the 120-150 tier i talked about.