Exceedingly annoying is working as intended. Unhandy and excruciatingly tedious could also describe the process.

Instead of flattening - pickaxing - flattening - lifting - flattening and so on...I would love a "flatten terrain" tool that would straight up flatten the ground any amount necessary and "add or remove" the required amount of stone from the inventory in the process. Or just remove, by all means, if that would be considered more "balanced".

Ever since I had land that I laboriously levelled glitch, reverting not only to its craggy original condition, but also to extreme mountainous type terrain I have been very frugal when it comes to levelling land. The first time this happened was in a Draugr village I had restored and repurposed as a foreign HQ, where I have been told it is a common glitch. Now I will insert vertical and 45 degree posts into the ground as foundations and build my flooring on top of them. Half submerged stone blocks also make great foundations upon which to build level structures on uneven ground. Now when I chose to repurpose a Draugr village, I will destroy 1 or more of the buildings, using the pre-levelled base on which to build or use for garden plots.

To get perfectly level ground using the hoe, I chose the height I want my land to be, set my camera for a straight down overhead view, then slowly move forward constantly clicking to level. This is the most effective method I have found after playing the game for over 3000 hours. Be careful to step back every now and then and survey your work as there are some areas that will not level, requiring one to add height or remove land using the pickaxe.

Land I levelled in a Draugr reclamation project: https://steamcommunity.com/sharedfiles/filedetails/?id=2900820733

The same land a few hours later after having glitched: https://steamcommunity.com/sharedfiles/filedetails/?id=2795535497

it flats to the level you're standing on, rather than spreading out the place you're pointing

putting logs down, standing on the log, and leveling it out that way gets it pretty dang flat. I did a castle that way once.

Hold down shift to make slopes (lets you aim up/down on a slope to sort of smooth it relative to where you stand). The flattening only goes a bit at a time, and not too much from where it's starting. You'll need a pick to lower heights that are too high, and you'll need rocks to fill where it's too low, eventually. You can only change the terrain something like 10 height tiles or the like (maybe 15?) -- so no caring a flat path through a mountain or anything -- but you can cut a road.

And nope... there's no speed up unless you mod. It's a labor. It's supposed to be. This is a pretty chill game that expects you to put in the labor. If it feels slow, go try out Wurm Online/Unlimited for a bit and you'll come back thinking this game is super fast.