The days counted, the proration applied and the rule behind each deduction stay attached to the payslip that used them. There is an endpoint whose entire job is to hand back the calculation proof for a payslip — because "why is this figure this figure" is the question payroll actually gets asked.
A run is a document, not a button. Created, processed, approved, marked paid and sent to finance — each a recorded state rather than a spreadsheet someone emailed.
Each step is its own act on the record, so a half-finished payroll is visibly half finished.
Statutory compliance · Attendance · Employee records · HR reports
Open the payslip, ask for its proof, and the reasoning is there.