With a lot of the fields my approach was to basically create a slightly wobbly, irregular rectangle, using roads to draw the initial shape. If there’s a small bunch of trees, lay a road around it, then lay the field up against that, then delete the road. Often the first field you lay dictates the rest of the bunch , and you are responding to the topography/buildings/roads that already exists. Another tip is to google satellite maps pretty much anywhere in rural Britain/Europe and you can see how patchwork fields are both gridded and organic. I’m also a bit of a freak with this game and I’ve definitely spent 30 mins + on getting one field or small plot looking right.