I believe different types of squats would be way better than using the leg press as a main movement. Also I feel one needs more then just one exercise for each muscle. You can't be getting enough volume. By what you're doing
i think the leg press is superior to squats as it isolates the quads and maximize the use of the quads and nothing else.
i also think that 1 exercise per muscle group is enough, if its the right type of exercise - for example i doubt someone doing pull ups will not get a great back or someone doing dumbbell presses will not get a great chest.
and as far as volume i do them three times a week where as most people would train legs only once per week.