Player skill level is a bit of an issue. A new player can not easily earn a vibe level of 10 just like that, but you don't want to give away snails for simply covering turf either. So here is an updated way to earn super sea snails and I will break it in two parts.
Part 1- on turf war you can earn 1 snail based on the following conditions: A vibe level of 4 or more for player levels 1-19, a vibe level of 7 or more for player levels 20-39, or a vibe level of 10 or more for player levels 40+.
Part 2- on ranked battle you can earn snail(s) based on the following conditions: 1 snail for C rank (C-, C, C+), 2 snail for B rank (B-, B, B+), 3 snails for A rank (A-, A, A+), 4 snails for S, and 5 snails for S+. Earning these snails will be based on your vibe and player level from part 1.
The ranked and turf vibe meters will be separate from each other the these requirements must be completed prior to the start of the next rotation. So here are a few examples:
example 1: near the end of rotation a level 50, S ranked, player earns a vibe level of 10 on turf war and 7 on ranked battle; the player is awarded 1 snail for completing the turf requirements but not ranked. The player then has to wait 24 hrs to earn the next snail on turf war, but they can still attempt to earn snails from ranked since the player didn't earn them from last rotation.
example 2: near the end of rotation a level 18, B- ranked, player earns a vibe level of 4 on turf war and 6 on ranked battle; the player is awarded 3 snails for completing the requirements in both turf war and ranked battle.
the vibe meters can also have a super sea snail icon to indicate when you can earn snails. A grayed out/silhouette snails indicates that you are eligible to earn snails, a filled in snails indicates you can talk to Judd to earn your reward, and then the snail will disappear on the vibe meter(s) indicating that you are now in the 24 hour waiting period and will reappear as the grayed out snail to indicate you can start earning snail(s) again.
I know this system is not full proof and there are still some issues like "what happens if I rank up or down?", I'll let you discuss that among each other and give constructive feed back. Again if you have a better way to earn super sea snails, fill free to reply.