You can lvl the crafters without touching them you know... Buy the grand company item HQ or NQ they request in market board and use it every day to lvl up te crafters if you don't like or ask a crafter friend to do the craft for you.

Now you are wasting more gil repairing at npc than buy a stack of DM6 which is 11700 or even free if you buy with GC seals. You can use it close to 10x and better you can even repair in middle of a fight!

Reaching 50 on a crafter doesn't take much time and effort.