Loose is where it goes wrong. It allows drag separation with the Big Daddy, which opens up a vent and the charge never gets a chance to pressurize the airframe. You want the masking tape to "seal" the NC shoulder against the inside of the airframe long enough for the airframe to pressurize and build relative velocity quickly between the nose cone and airframe as the cone starts moving forward. Then, once it "uncorks" and opens up the wedge portion to vent, the NC is already moving rapidly away from the airframe. Also, since the tape ring clears the airframe all at once, the remaining portion of the shoulder should provide little friction to hold them together.
All the strategies for filling the wedge are aimed at getting that same dynamic to happen. The only real reason to fill the wedge, IMO, is to have the "seal" farther down the shoulder, so the NC has a longer travel distance and can thus be propelled to a greater relative velocity before the uncorking happens. So they are still worth doing, and I will continue to do so, but I acknowledge that a proper tape fit, sufficiently tight but not too tight, is probably "good enough."