Anyone undersize their fuses?

It has been my experience that if I have a short it is going
to blow the fuse no matter if a 10/20 Amp.

That being said = what could be the worse case - you blow the small
Amp fuse and find out the load was higher than you thought. No Great Damage done.

The Amp meter is a different story as the power going thru it is huge.
On my race cars - I do not use it but utilize a Volt gauge instead. But
they are not restoration cars and are much more likely crash and I have
done so a couple times.