Yep, had my rear let go last year 3/4 the way through a 5000km trip, deflated rear tyre (obviously) and punched out an internal plug.
Had to ride it flat at freeway speeds for about 10 kilometres because of location, connecting ferries etc and goosed the tyre which bulged out at the sidewalls. Luckily the stars aligned, I found a replacement valve and workshop in a tiny little Tasmanian country town.
Had to replace the tyre though before I set off for home about 1500 kilometres away, which meant I paid more for a brand of tyre I needed, but wasn't my first preference.
Moral = change them every time you change tyres, or, get the solid alloy types and change the seals every few years.
P.S Don't leave right angle valve extensions on the valve stems as these can also accelerate the demise of rubber valve stems.
Cheers, Ricky