Erik Darling explains why simply looking at wait stats isn’t enough:
I’m going to be honest with you, dear readers. I’ve fallen out of like with wait stats.
Unless there’s a massive resource or blocking problem, they’re a bit bland.
Tuning a single query, I don’t look at them at all.
Sure, they can be a good detail when you’re painting an overall picture of a server, but they’re misleading a lot.
Erik makes a sound point. It’s usually a sound point when it reminds me of the Hayek quotation, “Mr. Keynes’s aggregates conceal the most fundamental mechanisms of change.”