You start at the top. Is your CEO on the board of multiple companies? Probably. Is your CFO an advisor somewhere else? Almost certainly. Does the COO help organ

You start at the top. Is your CEO on the board of multiple companies? Probably. Is your CFO an advisor somewhere else? Almost certainly. Does the COO help organise charity galas and political fundraisers? You betcha! If they're capable of "overwork" why aren't the rest of us? Start the crackdown at the top. Audit your C-Suite, go through their financials, track their minute-by-minute productivity, and ask them to report any external earnings. See how they like being tracked and treated like fraudsters. Once you've successfully tried out these techniques on them, move down to the senior managers.