Plug wires?

I swap mine out every 30K. Now, I know I have some good reason for that number, but to be honest, I don't know why or where it came from.....it's buried deep inside. Been doing it this way since about

1982, so it may be that BACK THEN, that was the wisdom and it may or may not hold today.

On the other hand, never had any problems related to the cables and have had a number of friends who have....

The distributor cap too?

OEM ignition (plug) wires, distributor cap, and distributor rotor should last at least 60K miles.

You can safely go 60K miles.

Today, many engines do not have plug wires and use a coil over plug setup.

yep, by swapping for new cables every 30K miles, you likely won't have any ignition problems, but your wallet suffers needlessly, when you use an arbitrary number of miles to replace them. If they're good quality and aren't overheated they should last 100k or more, in my view. If the engine starts misfiring, then's the time to look into new cables, I think.

At 45,000 miles, one of my factory original Nissan plug wires started arcing to the edge of the exhaust manifold heat shield 3/4" away, but the insulation looked fine, even when I sliced through the cable to check for any internal cracks or bubbles.

Generally speaking you test the resistance of the cables. If the resistance is over the specified value for your car then change them. Pep Boys has the Haynes manual that shows you how to check. Or Autozone's free online repair guide may offer some info up to '96 but should give you an idea.