Is There A Level to Star To Gear Tier to Ability Level Ratio Reccomendation?

Not really. For the characters you are using you want to get them as high as you can because they will be more effective. Even as a casual player, presumably there are parts of the game that you enjoy actually playing, and want characters that will do well at those? When you say a wall at 54 are you talking about with gear or with what exactly? A bit more detail of what you are trying to accomplish would help.