Payroll closed on time again this period. That tells you the outcome was met. It tells you nothing about what it cost to get there.
If the honest answer is 'quite a lot,' the issue is not effort. It is dependency.
These build slowly. Each one is survivable on its own; together they turn payroll into a function that consumes attention rather than earning trust.
Payroll depends on individuals whose knowledge was never written down. Leave, illness, or resignation becomes a business risk.
Spreadsheets, re-keying, and workarounds fill the cycle. Every manual touch is another chance to get it wrong.
Repeated fixes and supplemental runs signal that something upstream is not working - and they cost real time.
Without written procedures, payroll cannot be handed over, audited, reviewed, or improved with confidence.
Balancing payroll to finance and tax takes days instead of hours, and issues surface far too late.
Missing or delayed data from HR, time, benefits, or banking derails the run and eats the buffer.
The same activity is performed differently across the business, so assurance is inconsistent.
Skilled payroll people spend their week processing. Nobody is left to fix the causes.

It gets outsourced because it became too dependent on individuals, manual effort, and knowledge that cannot scale with the business.
That is the difference between a payroll that happens to work and a payroll you can rely on.