If you need to develop speed,coordination,and control,you'd be better off practicing with your actual peds & Kit.
Much better if you can watch yourself in the mirror.Try to record yourself playing to check for improvement.
Watch the movement of the beaters from time to time(they should move with consistency to each other) and make sure both pedals are of equal spring tension,and angle from the bassdrum.
Check-out other drummers' pedal set-up and method of playing!
To develop endurance,or stamina; cross-training such as biking, jogging,or running up & downstairs would help a lot.
..most of all, be patient....Youre not alone on this side of the table!