I had a case of cleanskins, with screw top caps, red wine. And I opened one about a month or so ago and it was still delicious - they are a few years old, vintage 2005, I'm a bit slow getting through my stash on my own.
And I opened another today and it hissed when I opened it, ie there was pressure in the bottle - eek. And it tasted horrid and was not getting any better half an hour later. So I tipped that one down the sink. Might have to warn people they have potentially exploding wine...
So even with screw tops (not stelvins) you can still get a bottle go off.
Casks - once openned - does it say on the pack somewhere, recommend drinking within a couple of weeks or something? I think it would depend on how much air you let into the cask when you let wine out of it. Or if the wine was really done fermenting when they put it in the cask or not. If it wasn't done fermenting, there would be stories of split casks or exploding wine somewhere.