The Senate terms of six years worked well with the provision that 1/3 were up for election every two years. Any limit should have been at two terms, with at least five years OUT of political office before running again. This, to prevent politics as a career. Limiting benefits to only time in office (no such thing as a pension) would help.
It was thru making government service a full-time occupation that led to federal politics being the lucrative career path it has become, the plethora of laws on the books, and the detachment of federal politics from the American People in favor of the benefits of "cronyism" ("Big (xxx)" lobbyists, activist organizations, unions, "bundlers", etc) whose priorities generally do not include the People in the final results, but benefit the politician's primary concern: self