This does work, but the process is crushingly difficult for my mother. (Try to explain to a 60 year old that you need to reveal the clip in finder. Trim it, save it, trim it, save it, etc for each part of the video. Then re-import those clips into iMovie and delete the original large file from your events). This could have been accomplished with one keyboard shortcut or menu command.
I'm opposed to creating projects to organize events because it doesn't make sense when creating a Christmas montage to open a project and look for a clip then find it in the events when you could otherwise just look through Christmas 1984 and pull the clip you want. It creates a dual paradigm.
More than anything I want to attract Apple to this glaring flaw in their product. I can't see the downside of in-app splitting of events which was a feature of iMovie v9. Why remove it entirely? I know it's a rarely used feature, it could have been suitably hidden to avoid accidents. It wouldn't frustrate the average user, but it has confused the ever-living **** out of my mother.