To get a horse to respond better to the leg?

I use to have to ride a horse like this at a barn I use to ride at. The instructor wanted me to barrel race her to (haha) I use to have one of the people I ride with help me and Id take her in a round pen id use leg aids and if she doesn't move then you get the person to just move her forward with a lung whip(Only to the gait you are working at). after she starts moving stop her after about one time around and then try to get her to move with just your legs. Keep doing it over and over until she moves without the use of the person. and then go to a different gait.