MondayA site supervisor orders materials by phone because the job cannot wait. There is no order document, only a promise.
TuesdayA second supplier is used for the same items because nobody knew about the first call.
Two weeks onBoth invoices arrive. Neither matches anything, so both are paid to keep the suppliers working.
Month endCosts are up and nobody can attribute them to a contract, so the answer is “it was a busy month”.
Quarter endThe company is profitable overall. Which contracts made that profit, and which quietly consumed it, is a genuinely open question.
What it actually costsSpending authorised after the fact, by paying the invoice
A purchase order that has to be approved before it commits anything is unglamorous, and it is the single control that changes the shape of a services business.