Most annual budgets are abandoned by March. They are built once, approved, printed, and then quietly diverge from reality until the whole exercise repeats a year later.
Three changes fix this. Build the budget from drivers rather than last year plus ten percent — headcount, unit volumes, price. When something changes, you update one assumption instead of rebuilding the sheet.
Second, run variance analysis monthly and in writing. Not to assign blame, but because a variance you can explain is information and a variance you cannot is a warning.
Third, reforecast quarterly. The original budget stays as the benchmark you are measured against; the reforecast is what you actually manage against. Keeping both is the point.