10/15/20 reagents from a hireling would be far more than you get in other crafts' materials from a hireling. More points spent on a hireling makes the mail come more frequently (at 3 points) or better chance of the other ingredients (at 2 points), not very much more of the base materials. Isn't it 5-10 for food/drink ingredients or only 3-5 raw materials typical for blacksmithing, clothing, woodworking?

My blacksmith and clothing hirelings where I have them only send 3 materials each time (the same quantity you gather at one material node) and sometimes trait gems or style gems or tempers/tannins/etc (usually green or blue if one does come, although over the long-term it can be a good source of purple upgrade mats). This is why I generally don't recommend most hirelings (except provisioning)... so I think if one were offered it would more likely bring 1/2/3 reagents and a solvent sometimes.

At rank 1, the hirelings for the hard crafts return just 3 raw mats (unless you're at the max 10th craft level, in which case things get weird). That's basically 1 node. This increases to 4 and 5 for ranks 2 and 3. So almost 2 nodes at rank 3 hirelings. That's the base and the only part that's guaranteed. Then there's the chance of getting various miscellaneous items--trait stones, style mats, and/or improvement mats.

10/15/20, in this context, is ludicrously unbalanced.

1/2/3 reagents plus 1/2/3 solvents as the guaranteed base drops for ranks 1/2/3.

With a chance of getting bonus reagents/solvents--the size of the bonus and chance increases with hireling rank.

Honestly, an alchemy hireling would be the only one to make sense anymore. Now that most hirelings effectively (or in the case of provisioning actually) don't drop gold mats they are not worth logging into. At least if an alchemy hireling gave a fair amount of mats it would be worth logging into as many alchemy mats are valuable and we all need pots frequently.

I'd enjoy it as a happy apothecary type.