Do managers really need to know 75 Key Performance Indicators (KPIs)? The short answer is no.
Firstly, there is simply no need for any manager to know 75 KPIs. That's like asking people to memorize the reference books in the library in case they ever need to use any of that information. You just need to know where to go to look things up when you need them.
Secondly, no business can have 75 Key Performance Indicators. They may very well have 75 Performance Indicators, but they cannot all by Key. In Bernard's defense, he does say in his article that you shouldn't use all 75 of his KPIs, but then why would he say that every manager should know all 75 of them if they're not supposed to use them all?
Can you imagine having 75 keys on your key chain? How would you keep track of what each key opened? How would you carry them around? Having that many keys is just not workable, and it's the same with Key Performance Indicators. You just need a handful of the important ones.
Bernard's list of KPIs is interesting but certainly not exhaustive. There are other potential indicators to use, especially industry-specific ones. Learning a list of possible indicators is just not an important step on the way to developing KPIs for your business. In fact, it's not even a necessary step.
The process of KPI development begins with your organization's purpose, not with a list of indicators. Once you've stated a purpose, you can then start creating (or looking up) KPIs that answer the question, "Are we achieving our purpose?"
Save your brain cells -- don't bother memorizing 75 KPIs.