The current 20 (meter I think is the unit they are measuring in) size limit of the terrain brush is fine for most jobs, but for trying to create mountains or any large geological formation, its insanely tedious to use. I think if the size limit was at least doubled to 40 it would be a lot easier to use, though ideally, I would go all the way to maybe 80 or 100 if its possible. Im not sure if the current limit size is just by design small or if its due to technical limitations, but if its possible to make it bigger that would be so helpful. I really hope this is something the devs consider or have considered because it would make life much easier for people who want to build this kind of thing.