I generally try not to take more than 40% condition out of my players a day through training and use greens to recuperate first team players after matches that are performing well, I only hard train my lowest fastest trainers as it seems they can cope with the higher intensity due to age and being low star. I find that every player's form benefits from once a day practice match training even the older slower trainers, like think about it from a real world perspective. Running isn't going to increase your form, just practice will do that. I generally train my first team and reserves separately. Excepting the fast trainers.