The Ombu Library, in the MDSAP aisle, has an article that explains the audit duration calculation for an MDSAP audit.
For an audit, the Auditing Organization determines the processes and audit tasks to include. MDSAP provides an Excel workbook that includes the standard time for each audit task and a place to record the included tasks. The workbook calculates the audit duration. The calculation model includes provisions for adjustments such a reduction in audit time for fewer than 45 employees or an increase in audit time to evaluate a correction or corrective action from a previous audit nonconformance.