Why, OH WHY, must I finish whipping the cream by hand??

Exactly--super easy to overbeat in a mixer. If you slow it down when it's almost there and watch it like a hawk, you can do it in the mixer, but even just stopping at soft peaks and using the mixer's whisk attachment to give it the last few beats can help make sure you don't overwhip.

You don’t, but I find that if I don’t, I over beat it. It’s just a precaution.