Final fantasy 13 question

[TheGame]

I seen all the old threads about FF, but I couldn't decide which one to bump... so just making one of my own.

I just have a question about the crystal grid. I'm only about 5ish hours into the game (maybe further). So far I've been able to easilly max every character on every grid with minimal grinding. I was just wondering for a first-time speed playthrough... does it make sence to keep grinding til I max everyone on every grid??

I've been thinking about just switching everyone to only having one DPS role, one support role, and having a couple of people have medic roles. That way when I recieve an extension to the grids they specialize in, I can max them out quickly from the gate.

I'm not sure what to expect later in the game, but should I be maximizing everyone in everything until the end to make the game a breeze? Or in the long run will it be easier if I minimize the amount of roles my characters play?

I really just want to see the story on this run, the next run I'll worry about getting exotic weapons etc.