I once worked for a company where they operated in the red for 95% of the year as they paid for project material costs up front. The CFO was quite open about how finances worked in our niche sector.

A client would pay an invoice and the balance would swing from -£20M to £0 and back down to -£15M for the next project within weeks! Revenue was in the £100Ms per annum.

As someone with almost zero business background it was a real eye opener how much we depended on a healthy relationship with the local bank manager. The business model clearly worked as they passed their 30th anniversary during my employment!