“The instructor’s responsibility is to stay with the student until they can comfortably perform the job to takt time following the standardized work. This is known as the ‘stabilization stage.’ The advantage of having team leaders act as the JI [Job Instruction] trainers is that they are already there on the floor. If they have a student they just trained, they have to stay particularly close to that person.”  

Toyota Culture  by Jeffrey Liker & Michael Hoseus (McGraw Hill, 2008) p. 129.