Operational upkeep is often reduced to patching. In practice a serious contract covers four families of work with different rhythms and risk.
Corrective. Security patches for the operating system, database engines and application dependencies. The most visible and most regular part.
Preventive. Watching the thresholds that announce a failure before it happens: disk saturation, memory drift, certificate expiry, provider quota reached, a backup failing silently.
Evolutive. Major version upgrades, end of support for a PHP or Java version or a managed engine, replacing a component the cloud provider has deprecated. This is the part internal teams postpone the most, and the one that produces technical debt.
Curative. Detecting, qualifying and resolving incidents, with a commitment on response and clear reporting.