The thing I would be interested in seeing is the empirical distribution of years of service (basically to see how much of an impact the proposal would have). Obviously, if we only have 10% in office for 20+ years that’s a much smaller impact than if 30-50% fit that category. I’m sure this is out there, but I’m not interested enough to do the digging. For your point, though, a good study would be with some measure of efficacy for these politicians and seeing what can be attributed to years of service and at which point we see a tiny marginal utility for further years of service.