Every guide here comes from a problem that appeared on a real site, was diagnosed properly and was fixed. That constraint rules out a lot of topics, which is the point.
They include the wrong turns. When a problem has four plausible explanations and the first two are wrong, that process is the genuinely useful part, and it is the part that usually gets edited out of tidy write ups. Knowing which check ruled out which theory is worth more than the final answer.
Where a fix carries a risk or a trade off, it says so. Some of these changes are ones we would not make on every site, and a guide that does not tell you when not to do something is not much of a guide.
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