Can you guys look at the Damn LeveQuests???

[Rhomagus]

Took me a day to grind CRP from 30-40 only using leves.

All of the advice in this thread is good.

Have good gear, use crafting abilities, sleep, craft specific food (I didn't do this one). It's not that bad really.

[Mikita]

I do both leves and regular recipe grinding. Either way, you get more experience the more difficult the recipe and the higher you can get the quality of your synth. Leves are still nice, IMO because they are free materials, plus you get EXP for turning them in (not just the synth itself) along with some useful materials that you can use later.

Rested Bonus (50% EXP bonus), Engineering Manuals (50% EXP bonus), and food (3% EXP bonus plus stats) really help.

Having multiple crafts leveled for different abilities also helps to control the synth condition, boost quality, or just get it finished.

Good luck with the leve availability situation. There are good days and bad days for availability, and the city with that craft's guild tends to offer more.