Bicycle man
Try keeping your contacts clean and tight in the first place; and, some extra money in your pocket.
All excellent advice.
However, let me insist that conductive grease is usefully and successfully applied to moving /sliding surfaces to improve conductivity.
As you doubtless know, "conductive grease" is the industrial, non-trendy name for branded products such as "SST contact enhancer, by Walker". It is also considerably cheaper when called that, rather than the branded equivalent.
However, if you have top-notch connectors you rarely mess with, you probably don't need it. If not, it can help improve the contact, especially the single-ended ones. Regards.