Ooh, lovely table Olicana!
Scatter terrain for generic points games in DBN has size limits, which makes sense given the small size of the board. Historical scenarios are set-up to whatever size is needed. Then, there was another factor of wanting the top plateaus to be a minimum of 60mm across to hold an artillery stand which constrained total width at the base.
1:3, aka a 33% grade is definitely ideal, but was too luxurious for this.
So I did some slope testing with the stands for the game. Infantry at 30mm deep would need to not slide off. With 3/4" thick foam ~19mm high, going out to 30mm worked, even dropping to 25mm in a few spots. Mostly a ~60% grade, with some parts going up as steep as ~75%. This has proven to work well in games. (For standard DBA games with close order infantry on 15mm deep bases, these hills would not work well at all.)