I'm really not convinced either.
As I said above, there are quite a number dotted around the Vale of Glamorgan, but even so, if you have sudden need while out on the road, and for some reason don't have your own tools with you, what are the chances you will be within half a mile or so of one you know about?
The ones in car parks where people may take their bike by car to start a ride are maybe more likely to get used, but even those aren't going to get all that much use I suspect.
I have never seen anybody using any of them, though that doesn't really mean much as I have never stopped in sight of one for any great length of time.