Tardis:Beware recursion

This wiki is largely maintained by a bot. And while bots are fast, a lean, mean category tree will make them run even faster. If you nest categories within themselves, you create a recursive loop that traps the bot in an endless cycle. So don't do it.

Examples
The most basic kind of recursion is where you literally put the category inside of itself, as in the case of adding category:Time Lords to category:Time Lords.

Most people don't accidentally do that kind of recursion, however, because it's obviously pretty silly. Instead, the far more insidious kind of recursion is where you put big, important categories within other big, important categories.

The classic example is Category:The Doctor. This should never go in Category:Time Lords. Instead, put the page The Doctor in category:Time Lords, and put The Doctor at the top of the in-universe category branch.

Otherwise, the bot will spend hours bouncing back and forth between categories under Category:Time Lords and Category:The Doctor. Why will this happen? Since the Doctor is a Time Lord, his category shares any number of pages and subcategories with Time Lords.

Now, this isn't to say that all categories about individual Time Lords should stay out of Category:Time Lords. Category:Romana is fine to go under Category:Time Lords because it's a very small category, and, importantly, it doesn't contain anything that's repetitive of what's already in category:Time Lords.