We use regular 6 foot leather leash nearly all the time. It is pretty scary when your pup bolts after something and rips the retractable leash out of your hand. They end up either continuing the out of control chase, or running away from the handle that seems to be chasing them. In addition, training is greatly inhibited compared to a regular leash. Saying that, there are exceptions now that Layla is over 2, ie. more mature and trained. For example, walking the beach at the ocean at sunrise with no one around. She will run 3 miles, investigating everything, to every mile I walk. She knows the limit of the retractable leash and does not test it, as she did as a pup. We also use a loose, as in not held, rope for training off leash control. She clearly distinguishes between all of three, and LOL, certainly knows when she is totally off leash.