Loaded question LOL
Not to mention HALF the people that reply to this will categorially deny doing more than 1 cycle per year
To take your question head on, there is no right answer.
Depends on your goals as well as your ability to temper these goals with a comprehensive awareness and understanding of al the potential hard you inevitably do to your body in the process.
In short, more cycles = more POTENIAL harm
It's inescapable reality.
That said, there is a responsible way to go about things so it is possible that those that run 3/year do less hard than the morons that run 1/yr improperly.
Run what you feel YOU need to but be prepared for the consequences and be prudent in your attempt to keep the risks at bay to the best of your abilities.
Lastly, certain health risks for one may not be the same priority to another
soem are concerned with liver toxicity issues while other care about hpta while others care about heart disease or BP so the replies to this query will be all overr the place.