I have just cleaned all of my connections from tube pins, interconnect, and ac power cords and cartridge leads. It does make a difference. How often do you do it?
Here is my method which is a pain but I do it only once:
1) Clean the contacts with isoprophanol
2) Polish, whenever possible, with a jewellery polishing paste (grren or white)
3) Clean again with iso to remove the paste leftovers, dry
4) Apply sparsely a dielectric grease (I use silicone-based Dow Corning compound for mil/airplane applications)
5) Connect firmly and try not to disconnect if possible; when disconnecting reapply a bit of the grease before re-connecting
I do this, but switched to G100 because G5 gets the stuff everywhere, but G100 is too much imo, so you need to apply it then remove as much as possible with a dry cloth or q-tip.
I think it's enough to apply G5 with a tiny brush, in which case one can is a lifetime supply...
I also use Furutech nano-fluid on terminations inside plugs and on any exposed wire to prevent corrosion, including on cables I build for ZenWave.