I have been watching Archengela's channel on YouTube. He described Star Trek as fantasy. And, according to him, there has to be consistency within that fantasy. I agree with him. There have been times when Star Trek wasn't consistent with itself. I find it frustrating that this is so. I wish the people in charge took the time to do research and work within what was established and expand upon what was established. Instead, they conveniently choose to ignore what came before in favor of telling a story. For me, one of the biggest inconsistencies was first contact between Humans and Klingons, as this was the A-plot of "Broken Bow". We have the version as given by Captain Picard in "First Contact". So, which version is to be believed?
They can both be true. Picard only said "Centuries ago, a disastrous contact with the Klingon Empire led to decades of war." He never actually specified that it was humanity's
first contact with them.
Consistency is a storytelling tool like any other, and with any tool there are times when it serves the story to use it and times when it serves the story to set it aside. The highest priority is telling a good story. Usually consistency supports that, but there are times when an excessive insistence upon it undermines the quality of a story. For instance, staying slavishly consistent with a mistake or an outdated notion from an earlier installment is not a great idea. And it's often possible to find a way to reinterpret something in a way that seems to conflict with how fans interpreted it but is still technically consistent with the letter of the statement, as with the Klingon first-contact bit here. Creativity is about flexibility, not rigidity.