You'd be surprised. Arnold Weinstock, who was running GEC when I worked for one of their subsidiaries in the early 90s, personally scrutinised every directors expense claims (both main board and subsidiaries) and was ruthless about disallowing anything he felt inappropriate. Once, his FD and right hand man tried to claim £50 for losses made on the outcome of playing golf with business contacts. Arnold red-pencilled it with the comment "Am I to presume from this that, had you won, you would have given the winnings to the GEC?". They get to be billionaires precisely because they do sweat the small stuff. Firstly, because it sets a good example to other employee, and secondly, because it establishes a culture of getting things right from day one. Arnold also used to refuse to sanction any redundancy payment which exceeded the statutory maximum.
Certainly not on the same level as Weinstock, but back in the day Tom Cowie, who then owned an expanding garage group, three finance companies, a bank and an insurance brokerage, still found time to ferret through filing cabinets (pre-computer days) after all the staff had gone home.
That was one way he kept his finger on the pulse of what what going on in his business empire. His attention to detail, not to mention his parsimony, was legendary.