Most decent CAM software has at least some simulation routines, which is helpful, but definitely not definitive. There can often be errors such as defaults that are bad in some situation that create a lead-in/out that tries to clear the tool, but actually digs the full length of it into the solid material, and this might not be noticed in the simulation.

I've also frequently mocked up styrofoam stock material and run the entire toolpath through that, which can be very helpful, but again, not definitive.

Ultimately, you need to just be really careful about the toolpath creation, and watch the first run like a hawk, which can take hours. Pausing and starting each new segment at a fraction of normal speed can help also.

The cool thing is that once you've run the toolpath a few times and can trust it, you can almost start it and ignore it while the part gets made (note that the operative word is almost).

Even with the difficulties, when you have a good machine and some skills (and patience), it is quite rewarding what you can make!