I can understand you.
You wrote "When the inertia sets in and distractions start to appear, its time for a little break, and then return refreshed.", I have to say that sometimes I need a "big" break before to return refreshed to an artwork, sometimes my "big break" is to work on another painting before to come back at the first ;)
A fresh set of eyes is always beneficial for progress. Likewise, a refreshed body is beneficial to an athlete. The trick, is making sure that break is not too long that we are sidetracked.
Yes, I too have reserve artworks always waiting on the sidelines should I reach an impasse.