Combat classes.

One miner and one botanist can generally keep up with my needs, though admittedly I'm mostly just crafting leveling gear and GC hand in stuff, very little to sell. However, so much stuff is retrieved by a combat class, one is nowhere near enough.

I'd initially gone 1 of each, then with HW gotten the other four. I had gone and made the four new ones two miner and two botany, but by the time they got near level 50 I found that one was enough to handle most of my needs. I'm now in the process of taking two (one miner, one botany) up as combat classes instead of gathering classes.

Another consideration : combat classes get 5, 7, or 10 of an item. Miner/botany are more like 10, 20, 30 of an item. And areas where they mix, such as turning hides into leathers, you need more combat drops than you do gathered drops.