Many contracts advertise 24/7 and deliver a mailbox read the next morning. The useful question is not the advertised coverage but what happens at three in the morning.
Our monitoring runs continuously and first triggers automated remediation. If the platform cannot resolve it alone, an alert goes to on-call with the context already assembled: which component, since when, which metrics drifted, what was the last change applied to that environment.
This pre-processing changes the nature of on-call. The engineer taking the call does not start by looking for what is happening, they start by deciding.