Hi Nico,
You can use a flat endmill - with or without a corner radius, or even a ballnose endmill - to perform a roughing pass first using one of the 2.5D milling operations to hog out most of the material first. Then come in with your desired finishing tool with the Parallel Carving operation and its Cut Depth to match its Max Depth so that the toolpath cuts the entirety of the piece in one layer of cuts. This is generally the fastest way to go about a relief carving because you are taking advantage of a larger cutter to remove more material faster. Just be sure to include a non-zero Leave Stock on your roughing operation so that there's some material left for the finishing operation.
You can also use the Parallel Carving operation itself with a larger cutter as a roughing operation, before you come in with your finishing cutter and another parallel toolpath that goes over the whole project in one pass. There is an example project on our Downloads page: https://deftware.org/pages/downloads
Both the Skull Fractal Pattern and Tree of Life projects employ roughing operations before bringing the piece to its final shape with a finishing operation. :]
- Charlie