A 13-week cash forecast in one afternoon

A short cash forecast does not need a model. It needs this week’s bank balance and an honest list of what comes in and goes out (sample briefing).
Write the payments you know first: wages, rent, tax, loan repayments. Then the receipts you are sure of, then the ones you expect. Keep the assumptions on one page.
Each Monday, replace last week’s forecast with what happened and roll the forecast on by a week.