I'm guessing that there may not be an 'onslaught of appointments' if it's starting to fail, and you're told that it's only got a year or so? (I'm only guessing). At that time, you may want to decide whether it's worthwhile to replace it sooner, rather than later, or to wait until it gets worse (possibly damaging your heart) and then replace or repair(?) it.
I was in my early 40s when I got my mechanical - at that time, they probably didn't think about more than 7 or 8 years on a tissue valve, so the choice of a mechanical was a no brainer.
So - how many appointments you have to put up with when your valve starts to fail may depend on how long you want to wait to replace it --- never an easy calculation.