long tossing is great for your arms endurance but just like long distance running, it will primarily increase stamina not just velo. I long toss everyday of the week because it keeps me stretched out and my arm feeling ready but I'm used as a closer, so you have to know your arm and how well you recover and what feels best for you. don't limit it to number of throws or a certain amount of time at each distance. for a starter I would long toss twice a week on the days of my pen, going back to max distance throwing as high as you need to getting it there on one hop. really focus on getting 25% effort 75% stretch working all the way to 75% effort and 25% stretch. then once you get good and loose come in playing burnout trying to keep the ball from your partners waist to his knees to find your release point. at 90 feet and 120 feet I throw my change up at full speed to work the grip.