The problem with term limits at the Fed level is that it should be matched with some sort of term limits for a large part of the FedGov employees also. While POTUS and his cabinet folk roll over every few years, many FedGov middle managers are in lifelong jobs and cannot be dislodged under existing Civil Service rules. These folks have set up their fiefdoms and can resist any pressure from an elected rep/sen because they know the pressure will be gone after the next election cycle.
Every non-elected FedGov employee down to about halfway down the E-?? pay scale should be term limited in their job also. This will eliminate the resistance (slow-walking requests, etc) done by upper to middle management may have to the party in power.
“many FedGov middle managers are in lifelong jobs and cannot be dislodged under existing Civil Service rules.”
They can be moved though—and offered lateral positions in Guam or Puerto Rico—which effectively destroys their influence and authority. If they refuse the transfer then they can be terminated.
The Republican Presidents just haven’t had the stomach or determination to get it done.