Reading logs slowly
Search is fast, and that is the problem. When I grep for an error, I find the line I expected and stop looking. The line above it often explains more.
Reading a log from the top, at human speed, is a different skill. You notice the gap between two timestamps. You notice that the same warning appears every hour at the same minute. You notice the request that never completed because nothing was written after it.
I try to do this once a week for the services I care about. Not an alert review, not a dashboard scan: just reading. It is slow, and it is usually boring, and every few weeks it finds something no monitor was configured to see.