So for the folks who stroke: I think a huge majority of people on this site own a fleshlight, or a stroker in general. The question is, what do you decide to be the point in which it has to get binned and for for a new one? And how much of it is a sunk cost fallacy where you don’t want to throw it out because you paid good money for it? I’ve got a tenga fliphole that despite the fact the plastic casing is cracked and that leaves half the suction features unusable… it cost a lot of money and it still works. The silicone is starting to separate from the case but it still fits in there. And yet cheaper ones have been chucked out after a single use, or small degradation of the surface! So what exactly is it for you that makes you feel it’s time to throw a stroker out?
Can’t comment directly as I don’t have a D and my Husband isn’t interested in a toy for himself.
I have a rabbit that is looking definitely past its best (rotation stopped working and the button surfaces have peeled off) however I refuse to bin him. He gets me over the edge fast every time.
It’s insertable surface is intact and clean so he stays does my “old boy” 
In the case of a stroker I would suggest that they are fine until the silicone surface deteriorates so as to make it unusable.
Honestly it’s probably time to bin it when the suction feature stops working but you can get new cases. So maybe if the texture/material is still ok and you have no tears maybe just get a new case for it?
My hubby has a few cases that are different colors but has not needed to throw one out because it broke. Has has gone through a couple of sleeves as the rubber started to not look so good and he just wanted a change.