The great rule of moral conduct is next to God, respect time.

Time is being placed just below the highest thing there is, which is a strong claim and a defensible one. Every other resource can be replaced or borrowed and this one cannot, so wasting somebody’s is a real harm even though nobody itemises it. Lateness, padded meetings, unanswered questions that leave a person waiting: each takes something that cannot be given back.

The practical version is mostly about other people rather than your own productivity. Be on time, be brief, answer promptly, and say no early rather than late. Whatever you make of the first half, the second half stands as a good rule on its own.