Anime Episode Numbering

There appears to be some inconsistency with the numbering of anime episodes as I was adding episodes for One Piece, and I was wondering if there was a "correct" system?

For example, One Piece, the episodes appear to be numbered sequentially.

However, in Black Lagoon (the first season), the episodes are numbered #10x, and in Black Lagoon: The Second Barrage (the second season), they are also numbered the same. In Bleach, the episodes are numbered #[season][episode], e.g. #101 for season 1, episode 1, and #1624 for season 16, episode 24.

I only noticed the difference after adding some episodes, and would like to confirm the correct numbering before adding any further.

@chrono8921: The numbering system is a little bit tricky when you're not used to it.

With long running shows such as One Piece, it's easier to number them by episode number rather than season since they never really have individual "seasons" as they just keep on going. But you've basically explained it yourself.

For short shows that only have one season, just use the episode numbers. But if it's a long running show with over a hundred episodes with no clear cut as to where a season starts, use the episode numbers.

For everything else just use the established #217 styled format

@cloudguy: Thanks a lot for the clarification. Just wanted to be sure that there was no uniform system for all anime series and that I wasn't doing anything erroneously.