Comments in the “Edits” tab will often explain why a tag is organized a certain way, so check it first before making an edit.
If you’re wondering why a tag is named/defined/organized a certain way, often the answer is in its edit history. In a tag’s detail page, click on the “Edits” tab underneath its list of aliases. The comments on these edit submissions often explain the reasoning behind them, sometimes at great length. If you feel like a tag needs to be changed or merged in some way, please look through these edit comments first. They may show you that an idea has already been considered and explain why it hasn’t been implemented.