This isn't a post asking for help, but something I just managed to fix caused me to wonder something - when electrical connections start to go bad is there a gradual drop off in efficiency of the function they take care of? Until this week I had assumed electrical connections were either working or not working, on or off. But what about still working but reduced performance? If performance drops off before failure there would be a case for routinely cleaning all the electrical connections. Same rationale as changing the oil.

It does sometimes depend on what the electrical connection is for. However a less than perfect electrical connection isn't going to help whatever is connected to work correctly.
There is a particular issue with Freelander 2 crank sensors, where even a slightly less than perfect electrical connection can cause misfiring, and sensor failure. Also things like a slightly loose bulb connection can cause high resistance, which leads to bulb holders melting.
So it's always best practice to have perfect electrical connections.

Thanks for the reply. I didn't know that about the crank sensor. The map sensor on the F1 has always puzzled me, I've never taken one off that wasn't full of gunk. How it can function properly like that I do not know. SO there's that kind of contamination, corrosion on the pins, and condensation. I'm certainly going to be including cleaning connections as part of routine preventative maintenance from now on.

Pins can corrode over time if in damp areas and connections can become brittle with age and heat and of course earths can corrode.
So electrical faults can often be gradual or intermittent.