You are definitely not alone on this, Maia!

I, too, farm the Toxic Spores on Kessex Hills. In fact, it's been on my back-burner to put together a series of farming articles (Toxic Spores, Rich metal nodes, etc.) for some time.

To piggyback on your observations, I wanted to offer a few additional details I've noticed.

Out of the 30 or so spawn locations on your handy map, an instance/shard of Kessex Hills will spawn just 5 (and rarely, 6!) of them. Once you discover them, they will permanently exist at those locations until the map closes. If you leave or taxi to a different map, expect a different arrangement of spawns. At each spawn point, a cluster of Toxic Seedlings (usually 4 to 5 nodes) will appear, and only one of those nodes will actually drop the desired Pristine Spore . Notably, once you discover which node in the cluster drops the Pristine, it will always be the one in that cluster; you can safely ignore the others which just drop Mushed Spore junk loot .

Another interesting behavior with the Toxic Seedling nodes is that they actually have a random roll of how many Pristines will drop. Usually it's just 1, but occasionally you will get a lucky roll of between 4-9 Pristines! Furthermore, just like other nodes out in the wild, you occasionally get to harvest a node multiple times. I find that this happens randomly; usually it'll just be one of the junk nodes, but sometimes you get lucky and get to double or triple harvest the Pristine node! I once squeezed 11 Pristines out of one node /humblebrag. The wiki doesn't verify if gathering bonuses assist with any of this, but I make sure to at least carry the guild hall boost. The placebo effect is strong with this one.

Maia is right that there are small groups that AFK at these spawn locations, usually at ones that are safely away from aggro. And, they'll camp on precisely the one node in that cluster that drops the Pristine. But, I also agree that this doesn't make for engaging gameplay at all.

My advice, instead, is to survey the map and discover all 5 (or 6!) spawns, and make a circuit around the map collecting each of them. By the time you've finished one lap, that's usually enough time for 10 minutes to have elapsed to respawn the nodes. You're multiplying your profit and staving off boredom a bit more. With an infinite-use harvesting tool, you could also just go ahead and collect the junk spores, which can be vendored to defray any waypoint fees.

Another advantage to doing a circuit on the map is discovering any Toxic group events that might be in progress. That also helps break the monotony. These events are of the form "Escort/Rescue/Defend the Vigil as they attack the toxic offshoot". The reward for successful completion is a Toxic Seedling node with guaranteed Pristine drop. Same rules as above apply: sometimes it will drop more than 1 Pristine, and very rarely, it can be multi-harvested. The events can be annoying as the Toxic enemies are scaled up and Kessex is often sparsely populated, but I have had success soloing many of these. And, I'll argue these things spice up farming life for those that accuse it of being boring. You get out of it what you put into it.

Doing these laps around Kessex can net me between 80-100 Pristines an hour. I'm not super efficient with these methods and often wander to gather other resources on the map. A focused approach will surely do even better. Personally, I only started farming it for raids, to help build up stockpiles of Toxic Focusing Crystals for the guild. So, if you're just into it for the money, I'm not sure how well this compares to other farms.

Sadly, it's not nearly enough throughput to keep up with my endless piles of Bloodstone Dust. So, I have succumbed to supplementing my farming with buy orders on the TP. Oh, my aching bags!