As a tailor, I need more netherweave than I get on my own in order to level/cap. After all, 3 stacks of netherweave=10 bolts of netherweave. Thats enough for two low-mid 300 level items.
It also makes just over 3 bolts of imbued netherweave (3 per). You need those to cap tailoring. The imbued pants takes 4 bolts and the robes needs 5.
So while we do get a lot of netherweave, it's not nearly enough to level quickly. I saw somewhere that we'll need around 2200 pieces to cap tailoring? At 3 stacks a day, that's still 36+ days of grinding.
Now, with that all being said, I still don't know how productive intentionally farming netherweave is. As mentioned above, doing quests that involve killing humanoids will generate a steady stream, and you'll get the extra rep/xp/quest rewards as well.
I'd also ask your guildies/friends for help. The non-tailor ones
are generating far more cloth than they'll ever need for bandages. Let them know that if they get you the mats (plus a stack or two extra), you'll gladly make them
the imbued bags. This is best while you're getting skill ups for the bags, but still works afterwards. The extra netherweave they'll give you can be used for higher level stuff. Plus your guildies will remember to send you their cloth, even after they're all bagged out.