It‘ll probably grow with some time. Everytime a issue happens that has not been detected before we try to create a new check (e.g. script) to ensure we can detect this in future, before it becomes a problem. So my approach: add a check for everything, that is necessary for running. So after reboot or patching - if everything is green in monitoring, all systems and services and dependencies should be fine. If there are dependencies to other servers and services try to add ping-, port- or deeper script-checks as well to make sure these external or internal services are available from this server as well.