Lee collet dies are actuated by the bottom of the collet being pushed up by the shell holder, so they have to be made for the length of a particular cartridge case.
Neck sizing does not touch the rest of the case, ideally, which is why a universal neck die with changeable caliber neck bushings and expanders is a theoretical possibility, but most makers size the die body to match a particular cartridge case so they touch down on the shell holder as the neck finishes sizing. Without that, you have to be careful you don't set a die too low and mash the case shoulder.
The Lee die is a unique design, incidentally, and makes the straightest cases. The accuracy potential is better than most and the cost is least. An unusual combination. Neck sized cases get too tight and have to be set back after awhile. Some find they do better set back a thousandth or so at each neck sizing. The Redding body does that job without touching the neck. Combining one of those with the Lee Collet Die might be close to ideal?