There is some credence to that thought, but keep in mind that while it worked out well with Truman, Eisenhower; Nixon, Ford, Reagan and both Bushes, not so much for JFK, LBJ, and Jimmah Cawttare.
Overall, an understanding of the military really helps a President weigh his decisions with more facts at hand, it’s not a successful solution to all decisions though. Many Governors can learn from overseeing the Guard units in their state, however to make those critical world decisions, it would be better if that leader had the experience and training of our military.
Yes, but look at the failure rate for those who weren’t previous military, or at least a Governor who was over the Guard for four years.