Patching fails for dull reasons: no agreed deadlines, no list of what is out of scope, and no record that the work happened. When I designed a repeatable patching process for servers and end-user devices, the aim was simple. Meet the compliance deadlines, and be able to prove it.
Set deadlines by severity
Write down how many days each severity level gets. Critical fixes and zero-day fixes get the shortest time. Put the deadlines in policy so they are not a matter of habit or mood.
Patch in rings
Start with a small test group, then non-production systems, then production in waves grouped by service. Give each ring a soak time. A bad patch should stop at the first ring, not reach the payroll server.
Write down exceptions
Some systems cannot be patched on time because of vendor limits or fragile legacy software. Give every exception an owner, a reason, a review date and a compensating control such as network isolation. An exception that is written down is something an auditor can accept. An unwritten one becomes a finding.
Keep evidence
Save the compliance report from SCCM or WSUS every month, along with the list of failed patches and what was done about each one. Use the same report each time so trends are visible.
Treat zero-days as a separate path
Agree a fast path in advance, with its own approval step and its own deadline. Apply the vendor fix or a mitigation, record it and move on. Deciding the process during an incident wastes the hours you do not have.
This approach closed an audit gap in my own work, and the same structure fits CIS and SOX compliance, where the auditor wants to see both the rule and the proof that you followed it.