A chart of accounts is the list of categories your income and expenses are sorted into, the folders your money is filed in.
It decides what every report can tell you. If materials, subcontractors and fuel all land in one category called job costs, no report can separate them later, however the question is asked.
The common failure is the opposite: hundreds of near-duplicate categories accumulated over years, so the same expense lands in three different places depending on who entered it.