The purpose of practicing is to gain control over some element of music, whether ear training, technique or an isolated passage or riff. Part of gaining control is eliminating hesitations, jerkiness and uncertainty. The goal is having complete “ownership” over what you are doing: you want to “know” that thing in and out.
For ear training, chose the speed that allows you to listen, duplicate and understand what you are hearing. Repetition and focus are key. You might need to play and listen to something hundreds of times before really getting it, and you will improve to the degree you are focused. When you are focused you are “there.” Only when you are there can you duplicate or learn something.
