Option A: Sequence
There's some regular formulaic difference between each track (e.g. 2x the length of the previous, first letter comes 3 after in the alphabet [C->F], etc.)

Option B: Strings
There's some short sequence of differences which repeats at least twice (e.g. track B is 2x the length of A, then C is .25x the length of B, and the playlist follows the pattern ABCABCAB...)

Option C: Strats
There are at least 3 groups of sequential tracks that share some trait which none of the other tracks share (e.g. 4 songs exactly 3:00 long, then 4 songs exactly 4:00 long, then 4 songs that begin with the letter B)

Any of the traits in question should be immediately visible and non-subjective - no recording engineers (or shared band members for that matter) or moods or instruments.