Should cuts always be made on keyframes? I was hoping for a more exact cut without any re-encoding and intend to delete the source files once I've extracted the parts I need so want to make sure I do it correctly and don't mess up the resulting files somehow. I've made a few test cuts on non-keyframes using copy for audio and video and playback seems fine.
The entry point of a cut must be on a keyframe. The exit doesn't matter unless the codec uses frame reordering. A video player may be clever enough to skip garbage before the first and after the last keyframe if cuts have been done not on keyframes.