Above is a before and after ignition capture, 96 Merc Tracer 1.9 SFI 4cyl, 42k miles.
Top trace is after, bottom trace is before plug replacement. On multiple firing ignition,
there are two or more plug firings per combustion event. This has to have an effect
on plug wear even on platinum's. The up slope at the start of the spark line (bottom trace)
of the first firing of the plug indicates high resistance, and shows up in the second firing
as well. After replacement, this levels out (top trace) and you will notice a slight upslope
at the end of the spark line in the second firing, this is a normal increase of resistance
as a result of running out of any fuel mixture to burn in the cylinder.

The gaps on the plugs were quite large, which showed up in the waveform,
the worst was at .080 (oem .052-.056), this plug is missing the platinum
button on the ground electrode indicating firing negative to positive.

This plug is missing the platinum button from the positive electrode
indicating firing from positive to negative.

Most of you are probably aware of Ford painting the terminal ends of original
plugs to indicate such. Even different colors for mated cylinders on DIS.

Here you can see the mating cylinders, if you look close you can see the missing
buttons on the electrodes. Left to right 1,2,3,4

Here are some plugs with various problems left to right, totally worn out
(98k gm platinum), fuel fouled, oil fouled, and detonation.

97 Mercury Mountaineer 5.0 V8 133k

Well, I guess you could say these plugs went 100k since they are the
original plugs from a 97 Mercury Mountaineer with 133k on the clock.
The owners main complaint was poor gas mileage, 8-9 miles per gallon.
This thing actually ran well and it was hard to believe after getting these out.
All of them came out easy except one and some penetrant helped in its case.

No doubt these are the original, look at the corrosion on the plug shell.
KV readings were in the 19-20 range on most of them.
I'll bet the coil pack was happy to see these go.