How are tracks added?

Each hour the search criteria linked to in the "Subreddit" column, on the Reddit playlist page is retrieved.

If a new post is found and:
Then an attempt to add it to all available playlists for that sub is made. 

What is the expected format of the post title?

A dash must be present in the post title. The dash is used to separate the artist name and the track name. Where the artist name is expected on the left side and it's track name on the right side of the dash:

Artist name - Track name

What not to have in the post title?

Any other information besides artist and track name are expected to be in capsuled in ( ) or [ ].
So that type of information can removed when searching for the track.

If not there's a chance that the track can't be identified and therefore not added to the playlist!

There's however an exception to this rule, which is when ( ) and [ ] contains either of the following words:
mix, version, live, acoustic, acapella, cover, instrumental, edit, rework

These words will be used when searching for the track name as long as the are located on the right side of the dash (track name side).

How does the rotation of the playlist tracks work?

When an playlist reaches 50 tracks, then any new track after that will replace the oldest added track in the playlist.

How often a playlist is updated depends all upon how often new posts, matching the criteria are available.