The non-convenience benefit of medal are:

15% increased damage to fox: If you spend coupon on fox in anyway, this is useful. By comparison, it's like 1.5 kage boost, or 15 coupon worth every fox, or 60 coupon worth every week, roughly 1560 coupon value. But only if you do fox and would find utility in the boost (I would)

20% coin in survival: ~120k a day maybe? I'm not sure... 21m coin overall. Hard to put a coupon value on this.... But it's worth something. Let's say 300.

5 extra ranked battle: this WAS useless, but with monthly event, this does mean 140 extra pts per month. Medium thread cost 30 each, so this is 14/3 medium thread, a 177 coupon value per month, or 1064 total. Granted, those c*ually be bought on discount, so let's say 800

80k coin, 2 bond scroll twice per week (weekend claim), which is 2m coin and 52 bond scroll. Let's say 50 coupon worth?

Stat bonus: frankly, this doesn't do all that much. It might let you squeeze by a ninja exam level earlier... maybe... but that's meh.

So overall, in addition to the 3600 coupon, we have an additional value of roughly 3000. It would still be 4200 "short" compared to monthly pack.

Even with the event refunding 900, that's still 3300 short.

So if you want best cost-benefit in terms of power, monthly card is the way to go.

Thou medal does make life easier on certain things.