There is no simple answer to this question as it depends on a number of factors, such as your fitness goals, what type of leg exercise machine you are using, and your personal preferences. However, in general, leg exercise machines can be a great way to tone and strengthen your legs, as well as improve your cardiovascular fitness. If you are looking for a challenging workout, then a leg exercise machine can be a good option. However, if you are just starting out, you may want to try a simpler machine or method of leg exercises first.