The large-scale crafting leves are a great source of massive amounts of mats, as the repeatables can be turned in 6 times. It's very cost-effective for certain mats if you choose your leves wisely.

Otherwise yes, it's a time vs. caring factor. At best a L leve will only give 60% of the xp of 10 equivalent normal leves, but in like 20% of the time of the latter.