Reducing Garage Band file sizes

When using garage band, I recorded a practice session. Later, when I tried to singulate the songs into individual files, the file size is still the whole practice (7G). I tried "Split regions at playhead" and deleting the unwanted regions to no avail. I also tried copy paste / cut paste into other files and new files and nothing works. It also behaves inconsistently (one file was fixed this way). This is a clear difference from the old version(s) of Garage band and this one. I used GB because it is easy to use, but that appears to no longer be the case. What gives?