Stopping and taking some time off for either drawing lots of magic from enemies or playing cards and modding them into magic can be less waste of a time than having to summon GF's constantly for the rest of the game. It's so annoying to see Shiva headbutt an ice crystal for the 120th time. D:

You don't really have to learn which magics are good for what attribute either really, just get lots of magic and let the auto-junction do the job.