Actually, for blade fuses, you are right. I just remembered this Youtube video I watched some time ago. He measures resistance for various brands of fuses and calculates the variance from spec. Then presents a table showing how Bussman and Littelfuse are superior. Thanks for reminding me about this!

 

Also fuses can degrade over time, if low quality. They might not hold up to normal vehicle vibration, or the composition of solder might degraded.

 

Some, yes. I've worked on an airworthy B-17G bomber that still had the original fuses. What gave problems was not the fuse, but rather corrosion on the terminals. I once fixed a problem with the starters on engines 1 and 3 being intermittent by brushing the heck out of the terminals with a wire brush. That snagged me a highly unpaid job as the in-house B-17 and other assorted old stuff avionics and electrical systems guru for the museum. LOL! That was fun while it lasted.