That's interesting. I always thought that the 6 ft was too short. But perhaps it's too long? I run into trouble for instance when practicing changing sides. We were getting use to walking a board first on the left and then on the right. Chi Chi does great off leash but on leash when I have to switch hands , she ducks because the slack in the leash hits her head (which she hates). Same with finish in obedience.
While the only general requirement for the leash in AKC obedience and rally is that it be either cloth or leather, and long enough that there is slack in the leash when heeling, in practice, NO ONE uses a leash longer than 6 ft. Not only is there no need, but it is hard to manage all the excess. If the dog is in proper heel position, even with the SMALLEST dog, you'll have a good portion of a 6 ft leash rolled up in your hand. You need a 6 ft leash in AKC Beginner Novice and CDSP Starter Novice because both those classes require the handler to move (away from the dog) to the end of the 6 ft leash for the exam. In Novice whether it's AKC obedience, AKC rally, CDSP obedience, whatever, the length of the leash is totally up to the handler, as long as they are able to maintain a slack leash. (tight leashes, even if momentary, cost points, and if it is constantly tight, is an NQ in any venue)
I'm not sure what you are doing that requires you to change sides... This isn't something we do in formal obedience EVER, and I've only heard of it in Rally-free, but at levels where the dog wouldn't be on leash anyway. If you are talking about agility, agility is a TOTALLY off-leash sport. I know that some training places have people start introduction to agility equipment on-leash, it's not a way I like to start. If my dog isn't pretty darned good at sticking with me, s/he isn't ready for agility IMO. If I have a puppy who MIGHT wander off in the early stages of agility, I attach a light-weight string to their collar (not a leash, because I don't want anything that can get caught on anything) so that I can quickly step on it if the dog thinks about leaving.
And yes, to go in the ring in Novice (or Beginner Novice) in obedience, you DO have to get used to working on leash again for heeling. And a big part of that is the HANDLER learning how to avoid interfering with the dog with the leash. But you can finish either way in obedience, and if you finish left, there is no reason to tangle with the leash. Rally Novice is a little trickier, because there ARE moves where the dog needs to go around behind the handler, which requires the handler to switch leash hands behind the back. You also need to walk around your dog holding the leash, but at least you can se what you are doing, so should be able to avoid hitting your dog with the leash.
For the moves where you have to pass the leash behind your back, I suggest using the lightest weight leash possible, so it is the least unpleasant experience possible, and use tons and tons and TONS of cookies as you practice MANY times, so that they learn to associate the movement with something good. Then they will learn to ignore the silly leash! Remember, you ONLY use the leash in the ring for the very beginning levels of obedience and rally. After that, the leash is just a way to get from the crating area to the ring. The moment you step through the ring gate, you give up your leash anyway!