How does Title Separation work within the categories?

Title separation can be assigned to each category separately. Here's how it works: If "I'm a Believer" by Smash Mouth is in “90s Hits”  and you’ve set that category’s  separation at 30 minutes, and "I'm A Believer" by the Monkees is in “60s Hits” with a title separation of 2 hours, then these two songs will be separated by 2 hours which is the larger of the two title separations.
Title Separation works only across categories.  If a Nostalgia station has three versions of “Fly Me To The Moon” all within the same category, the Title Separation setting on the category is not applied to them within the category.  It is only functional as related to the same title that may be in other categories. If you have more than one song of the same title in the same category, they should be spread in rank order. Like, if the category ahs 200 songs, place one of the songs at position 50 and the other at position 150. Then they’ll never be scheduled close together.