On the Category Rules screen, I see: Maximum Number of Choices and an option to "set automatically." What exactly is that feature?

Music 1 always tries to schedule the songs in Rank/1-2-3 order.  But your various formatting rules will regularly preclude some songs from scheduling immediately when they come to the top of the stack.  So, if song #5 is at the top of the stack and it can't fit into the next slot to be scheduled, Music 1 will look down to the next song.  If it passes with no violation, it will schedule that one.  Then it will try to place #5 in the next open slot of that category.  So, instead of always scheduling the songs 1-2-3-4-5, they might get scheduled: 2-1-3-5-4.     The Search Depth (maximum number of selections) gives Music 1 more choices for each slot.  If #1 won't fit, it tries #2.  If that won't fit, it tried #3. Generally, you want the number of choices to be about 10 to 15% of the number of songs in the category.  Thus a category with 50 songs, should have a Search Depth/# of Choices set at 5 to 10 or so.    You do not want to have HUGE search depths.  Setting the 50 song category with for Search/Choices at 30 is not good.   This because of something else you want to happen.  Say that 50 song category is designed for an 18 hour turnover.  If you have a Search depth of  5 to 10, then some song might get it's next repeat play 20 hours later...or one might get a repeat play 15 hours later, depending on your rules and such.   So you get a bit of a spread, but the repeats all come within a reasonable acceptable "window".     But if you have a big, big search depth, then in the worst case, some song might get a repeat play 5 or 6 hours later, or 30 hours later...way outside your planned rotation pattern.  This scenario is rare, but it could happen.    So keep the # of choices set at 10 to 15% of the category. If you click the button that tells Music 1 to set it automatically, then if you add a lot of songs to the category or remove a lot of songs, Music 1 will automatically adjust the setting for that category.