Wages

From “source” to the financial statements is the direction of testing for completeness …
From the financial statements to “source” is the direction of testing for existence.

So if you think about a payroll system ,,,
Time records (e.g. clock cards/timesheets) -> payroll calculations -> payroll processing/payslips -> totals recorded in ledger a/cs -> included in financial statements.

Since nowadays processing of the payroll/payslips is one and the same process, the more relevant test for completeness would be to start with timesheets … trace hours to payslips … etc.

But actually, the greater risk of misstatement in the payroll is OVER rather than understatement (consider – if you weren’t paid for hours you’d work you would complain!) Overstatement could arise, for example, if employees are paid for hours not worked – or paid at too high a rate, etc – this doesn’t have to be fraud (e.g. “dummy” employees) – but could simply be errors – only they’re less likely to be reported by employees (who minds being overpaid?!?!) So the direction of testing from payslips is more likely to be “backwards” to the time records – to ensure that hours were worked/overtime hours were authorised.

Your 1st is a test for completeness but your 2nd is a test for occurrence – because you are going “backwards” what from has been paid for and agreeing to timesheets that the hours were worked (i.e. a valid expense for the entity).