The average woman is on HRT for 5 years. It's safe to be on HRT for as long as needed to treat symptoms. Winona generally suggests pausing medication after 2-3 years to see how you feel. If you feel fine without the treatment, it's a good time to stop. If the symptoms return, you can resume medication. You can continue to do trial pauses every year or so.
You can stop taking HRT at any time with no adverse consequences. Most women feel better on HRT, so they stay safely stay on the medication for several years. But if you decide it isn't for you, stopping the medication is perfectly safe.