SeeMeCNC Rostock MAX v2 User Manual page 78

Amount is expressed in degrees from vertical and tells the slicing engine to generate support
for any feature that meets or exceeds the specified angle. In the setting shown above, the slicing engine
will generate support at points where the model "overhangs" 45 degrees or more from vertical.
20 deg. overhang.
As you can see when your angle increases to 45 degrees,
each layer has much less surface area to adhere to as you print.
This is where support comes in handy. It provides that underlying
structure for those layers to build upon.
As the angle increases, the underlying surface area for each layer becomes smaller and smaller
until there's simply not enough surface for the next layer to adhere to. In these instances, support
material is practically a requirement if you want your part to print at all.
Now that you've got a good handle on why support can be useful, let's go over the parameters
that you can tune to get good support that is easily removable from your part.
Rostock MAX v2 User's Guide
When you've got a part feature that's only 20 degrees or so, each
layer can easily be supported by the layer underneath. This is because
as the part height increases, the horizontal dimension increase is less
than the extrusion width. This means that each new layer has a solid
foundation to adhere to as it's being applied.
75 deg. overhang.
8 – Advanced MatterControl: Settings – General - 78
45 deg. overhang.