I had uPVC glazing fitted in 1982. Since then I have had two panes replaced, one front and one back and the front is south facing.
I recently noticed that another south facing pane had blown but what I also noticed was that two of the windows, one north and one south facing were no longer draught proof. This became evident when my neighbour had a log burner installed and we could smell it when he lit it!
30+ years is a good life for DG so I decided it was time to have the lot replaced and I have certainly noticed the difference, particularly with sound proofing as the new panes have a bigger gap in them now.