In the real Naruto, Kage last for a pretty long time- I.E: Minato and the Third Hokage, Hiruzen. Minato was a short lived Hokage, with Hiruzen re-taking the reins for a long future. Putting a time-cap on the time a player will happen, but it needs to be longer than a few months. With what Vreg said, automated re-elections will solve inactive Kages.
A solution to a poor Kage - If there is a council of sorts for the villages like in the series, allow majority veto power, allowing them to over-throw the current Kage in place followed by a re-election for the next.
If there isn't a council, simply implement one in the future or put it up for public majority instead. I mean, in reality people revolt if there is a terrible leader who is bad, cruel or refuses to give up leadership, look at the revolutions in the past: American Revolution, the Haitians, French, etc.
TL;DR - Make the Kage term lengths more than 3~4 months: add veto systems for the crappy Kages that /WILL/ occur. inb4 dictatorz.
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