How do you manage SQL Server? Do you have a list of rules that tell you when x happens, you do y. Or if y doesn't solve the problem, you do z? Some of you have guidelines like that, though it's likely that the way you solve problems is somewhat internalized and you adjust your "rules" or "steps" based on the situation. Do you reduce or increase parallelism when you have high CPU? Either change might be the solution, depending on the causes of an issue.
SQL Server is complex. We can't easily reduce the solutions to problems to a set of rigid protocols that ensure optimal performance. If we could, there truly wouldn't be as much of a need for DBAs as there is. Consultants and experts are well paid, and often very busy precisely because SQL Server is not so easy to tune and optimize in many organizations.
That's a bit of the point I saw in Grant Fritchey's "Be Cautious Offering Guidance" piece this week. When trying to help someone improve performance, or reduce issues, or anything else, you can't often give someone a rule of thumb that just works. You can't give them a one sentence solution. Most things in life aren't that simple, and neither is working on SQL Server.
The environment in which your application runs is complex and there are lots of variables that can affect the advice or guidance that an expert might recommend. It's the reason we see DBAs often saying "it depends."
Because it does.