I concur with Goergehifi’s point regarding corroded fuses.
Corroded wouldn’t be the right word, I think stressed through many turn on currents and more crystallisation is more the way to explain it, which will "harden" the fuse element, and cause it to blow one day when it can’t flex any more.
This is why incandescent light globes are at their brightest just before their restive element blows one day, again always at "turn on".
A slow-blo fatigue ageing right to left
https://peakpinball.com/wp-content/uploads/2013/01/fuse-8312-640x426.jpg
A fast-blo fatigue ageing left to right
https://i.stack.imgur.com/0uqWX.jpg%20
Cheers George