Havin every DoH on lv 15 is the best thing you could do and they will save you a lot of synthesis fails or oppurtunitys for HQ :3
I find myself often in the place where I have an 'excellent' up and can go full HQ because I'm simply lacking on CP :/
I wouldn't finish everything in the crafting log tho. Since I hit lv 20 I'm doing leves (went from 20 until 30 just from a lv 15 leve wich basically made no efford) I can go from lv 40 to lv 50 simply by making Peridot earrings, peridot and mythril can be gathered by a mere lv 30 miner so it's the best way for me to do so with no cost except of time.
When you hit the higher levels or go all the way to lv 50 it's damn easy to craft every recipe below you, so you can complete the whole log easily and can go full HQ. That way you can make some extra money with less efford and without having your whole inventory filled with useless stuff you'll only throw away ^^