Well firstly, when I said "getting through a level without ever taking a hit", I meant it (implicitly, rules apply all the time you're playing, not just all the time you're getting things right). A single hit would mean challenge failed.

Originally the article neglected to also say "no reversion" (i.e. single segment), but I've now corrected that oversight by adding it. In particular that outlaws anyone cheaply reverting quick when they see they're about to get hit. Wouldn't want any of that.

As with any rule set, you could also take the approach of reverting each time you foul up (or for any other reason), to get through in piecemeal 'segmented' fashion, but that isn't the real deal of course. It could be useful as practice and learning though - or if you find the challenge just too severe.