It is okay to use an inner thigh machine from time to time in your workouts, but I would recommend using other exercises also. (best-leg-exercises.com)
1 legged and balance exercises will work your outer thigh muscles much harder than the seated outer thigh machine. (best-leg-exercises.com)
The inner and outer thigh machines don't boost the metabolism, so no extra calorie burn or fat loss. (fitnessdoctrine.com)