Screw it, web's gone cheap on Behemoth, I'll share what I did for leves. The trick is that completing any leve at all cycles the rewards for all of them. So if, for example, you finish a botany leve then it also cycles all the other classes leves too. Using this you can fairly easily and quickly cycle through leves if you have a large number of allowances (took me maybe 30 allowances to get 400 webs), and it also gets you useful xp.

I found this was good because I could then level other crafts and botanist while waiting for the appropriate reward to appear. Plus, once you get web it seems to appear for a good run of leves. I'd regularly get at least 80 web before it either switched or I got off. The only issue here is the number of materials you actually need. If you buy base materials then The Telltale Trees ends up costing about 100 gil/web, largely thanks to shards (I'm also doing LTW, so crafted my own hard leather). Obviously you could gather mats to drop this cost, although you need a lot of shards. Getting Handsy also gives diremite web and is cheaper, but also gives less web per allowance. I personally didn't do the level 25 leves, since at least one of them actually required velveteen, but you could do them too.

Why do I say level other crafts? Because you get a ton of xp just from making the items and turning in the leves for WVR. I went from 23 to 27 just earning my webs, hopefully crafting them should put me up to linen.