One of the issues I rarely consider when looking at democratic reform is term limits, although I am in favour of them for Mayors. I found this paper, Term limits in parliamentary mandates – Democratic renewal or disruption? published by the European Parliament. I note that they are more common in Presidential republics, as in Parliaments, people often consider serving on the back benches as an apprenticeship for government.
It presents the arguments for and against and catalogues those that exist, both national officials, mayors, and even intra-party restrictions. They are not common; funny that.