In bridge, do people go through cycles of under- and -over bidding?
There is a famous anecdote of Hans Kreijns (playing with Bob Slavenburg) overcalling Benito Garozzo's 4 Spades pre-empt with a 4 Spades overcall, on 4 to two top Honours, sometime in the 1960's. That's an overbid.

Seriously, when I learned to play bridge in the early 1970's, overbidding was everywhere. Precision had just become famous, and everyone was opening ratty 10 and 11 counts because C.C.Wei's Precision team did it. 

Since then overbidding has declined in the bridge company I keep, and so has underbidding. Of course, it is not the same company: the quality has increased substantially, and the bidding has generally become more accurate. Less overbidding, and less underbidding, because the bidding is simply better.