A common problem arises having to do with modern cable slipping at the derailer clamping binder bolt on older campagnolo derailers.

This because the cables are thin enough to fall almost flush within the groove.

The fix is to file the clamping surface, relieving perhaps .020" of aluminum there so as to make the groove shallower.

Stainless steel cables are wonderful, but should never bear against any stainless steel guide or run in un-lined stainless steel housing (bare coil type).
The problem has to do with resultant cold-welding friction that no grease can fully prevent.

Many builds subject the shift cable path to a tight radius, where a thinner 1.1mm cable will better form straight tangents adjacent to said bend radius. The result is better feel at the lever and more-precise shifting control, because the cable acts less elastic when the tangents are straighter.

Wherever possible, I secure a short section of plastic "noodle" tubing where the cable wire might contact a metal cable guide near the bottom bracket.
Secured in place with silicone glue or epoxy, it always makes the shifting better even if the guide was previously well-greased.