Can a workout routine done twice a week be augmented to be as helpful as if it were done every day?

This can be done and we would say this is a good average routine. It can be supported by the belief quotient of most individuals using our prayers, with the caveat that those sessions that are done be meaningful ones, and not a minimal showing, because otherwise that is all that could be done on the intervening days. So those days when exercise sessions are done, need to be honored and given suitable commitment to thoroughness and rigor for the augmentation to be meaningful.