It's not guaranteed. People are abnormal. I'm abnormal and don't gain muscle like others and I am constantly training to failure.

Gaining muscle becomes really complicated for some people since not everyone has the same hormones, androgen receptor density, myostatin levels, etc. Some people grow like freaks and others never do. I can sympathize but I am skeptical of 99% of people since most I've seen also don't do every thing right and it's clear that's usually the issue.