Level-music pairing has always been somewhat of a big deal for me. In most of my newer packs, I've adopted a system similar to that of Lemmings 3D, where each tileset has a couple of tracks associated with it, and for individual levels I choose which one of the tracks I feel best fits the level. (Of course, by default this is how my Lemmings 3D pack worked, but even my NeoLemmix packs have followed this system since Lemmings Plus V; with Lemmings Plus IV also later being patched to use this system too.) In my older packs (as well as Lemmings Plus Alpha, where I went back to this system due to it using the official tilesets rather than my custom ones), I used a more traditional Lemmings style of that the music depended on the level number. This did not mean music-level correspondence was less important here; instead, what music a level would get was always a strong consideration when determining the overall level order. This is why, for example, when I slightly tweaked Lemmings Plus I's level order a while back, levels were often swapped with another level that had the same music; as well as why LPI and LPII have custom music rotations specified that emulate the older behaviour (ie: track selection restarts at the end of a rank) instead of accepting the newer behaviour (ie: if a rank finishes on track 3, the next rank starts on track 4).