Your disclaimer likely will not shield you. Might help if you spelled purpose correctly if it's going to be at the end of every single post.
There are no more than 2 gather quests per rank at 20-30-40. My Botanist is rank 31 currently, the rank 30 leves I get barely put a dent in my SP to next rank even if I squander my Guardian Aspect on all of them. You need to hit a bare minimum of 35 before rank 40 leves are offered to you.
By the time you hit rank 40 the SP per leve is fairly low again, there are currently no nodes above rank 5 so you have to very slowly grind out on the leves and the random rank 5 nodes you encounter. Many of these nodes are far from being safe to harvest from, which is why you'll see the majority of your high end gatherer's living around Camp Iron Lake.
I really wish they would add rank 50 leves as well as some gathering quests in the future, but I know that will have to wait til the battle changes and other more important aspects are touched on. Hopefully the DoH and DoL jobs won't be left out in the cold.