The most common coordination failure I see is someone dropping cover for themselves at the exact moment a teammate needed it more.
It is worth being explicit about when cover is actually the right call. If you are taking fire and can break the firing line by moving, move. Cover spent on a problem that repositioning would have solved is cover that will not exist ten minutes later when it decides the match.
The other half is announcing it. Cover that nobody knows about does roughly half of what it could.