I took a few accounting courses in grad school. I once knew my debits versus my credits. Knew all about original issue discounts, goodwill impairment, and other such trivia.
Knew GAAP and FASB. Just showing off now.
I ran businesses for 33 years. I needed to know more about accounting so I hired good accountants, retained good accounting firms, hired a good Chief Financial Officer, got second opinions, and I studied the subject on the mean streets of the business world.
CEOs and founders need to know some accounting — financial accounting, managerial accounting, tax accounting. What I knew saved me a lot of money.
One of my interests is the progression of ratios in a graphical manner — pick a financial ratio and graph it such that you can see the trend at the bat of an eye. That tells me something.