The line of reasoning I referred to is not about economic cycles, which are taken to be independent of party politics. The reasoning goes that if -- for example -- the Nixon-Ford or Reagan-Bush years had stretched on and on, due to the failure of Democrats to come up with a credible successor, then the backlash would have built and built, and the electorate would have turned further and further left. Which, of course, is a big if, and I don't actually buy the theory.
Apart from anything else, I'm personally somewhat dependent on state paternalism and so I tend to vote centre-left because I rarely have the opportunity to vote for any real left candidates.
In the remote past I have stood outside in the rain or the baking sun, handing out "how to vote" fliers for centre-left candidates. These days it would take the imminent election of an insane fascist to get me out there for them.