I get a chuckle out of all the conversation about what is "supposed" to happen. Since all this is local tradition, the locals can decide what they want.
IMO, we put way too much emphasis on "crossover", AOL and bridging. For far too many families, this simply creates a big opportunity to leave the program -- we've "finished" Cub Scouts and now get to decide whether or not to join a Troop. I'd do away with all the hype and focus on making the fifth grade a seamless transition from Cubs to Scouts. You start the year as a Webelos II and the next thing you know it's June and you're at Boy Scout camp with a troop.