To lube or not to lube?.

I just use some generic dry PTFE spray on the cables when installing them.

I've just replaced a gear cable to which I applied waterproof grease. Seems OK so far. Cable looked like normal steel, hopefully stainless. I have memories of rust and sticking cables on bikes long past.

No lube necessary for standard ss wires and teflon lined outers.
Go for full length outer casing if you want the cables to remain smooth for longer.

Cables that have not been precoated benefit from lube- for example rock and roll cable magic is a decent product. The type that come with fancy coatings just leave alone until you replace them.

I prefer cheap cables replaced regularly than messing about trying to improve old ones though

Mine work as intended in all weathers without any lubrication until they become bad enough to need replacing. GT85 is only a stopgap measure.

If you shove oil or grease in a cable housing it is likely to attract dirt and further gunk it up. But as with so many things, opinions vary (and I don't take anything written on Bikeradar as gospel).

No.

If a cable has got particularly sticky I will squirt some GT85 in one end it and pump the brake/shift across a few times to loosen it up a little but this is only a temporary measure - it needs replacing.

I believe wet lube would not be a good idea as it is a viscous, almost sticky compound.

It might be ok for drivetrains in the rain, but would have the effect of clogging up the inside of gear cables.

If anything, a drop of dry lube which does not attract and hold dirt, or possibly some WD 40 if you think water has got in.