One thing with RB that you can actually see on disk;
When you are making edits, these edits are stored as temp files and kept track of during playback. It is not until you Save that they all get assembled together again.
So Saving often can work as well as Bob's open/close routine.

As you can imagine, after 100 edits, RB is trying to keep track of 100 temp files. Anything in the system could cause a hiccup with this. Saving clears the temp files and reassembles things. Anything from generate to regenerate to cut or copy is an edit that gets a temp file.
This is what allows the undo function.

To see this, check where your Temp Audio Directory is located. In the middle of a session, take a look at this directory to see all the edits being handled.
This is another reason to use a separate drive as the Temp Directory.
If you don't, by default I think it ends up in the Windows temp area with hundreds of other temp files. Maybe someone else can verify this.
I have mine set to its own disk with plenty of space for years now.

Make your sound your own!
.. I do not work here, but the benefits are still awesome