The 20 points a day is not guaranteed. I think most people can only get about 12-15 pts on average a day. So that's like 84-105 pts. With that, i can barely get 5 DPB hidan frags which is worst than the other F2P event that has him in it like 2-3 weeks ago ( I got like 7 frags there). I guess i'll just spend the ramen on the medium refine (3 pts per frag). If you use the cost of ramen 10 coupon, each medium refine would cost 30 coupon. This is lower than last week's Lucky star wheel where each medium refine only costs 2 stars (and u should on average have AT least 2 stars per spin). Each spin costs 20 coupons. So it's actually cheaper to get medium refine rune last week. Luckily i spent all my coupons on that wheel after seeing the events for this week.

well i see that in other posts, people complain that they got 2 ramen when they spent 400 stamina.. So my estimate maybe even too high...