I certainly break my journey from time to time. In the past 2 months, I've broken my journey twice and continued it on another day in both cases.Buy it once you do.
Split your ticket at the break point. It might even be cheaper!
Yes, OK, you can't break overnight on a whim, but exactly how many people do that? I'd venture somewhere around the 0 mark.
If we include day tickets then I've done it another time too.