Sometimes on set you don't get a second take. Do your work before hand and be prepared to do your best and do it fast. There are also a lot of distractions on set that aren't in class (unless you're in Brad's class where it's all part of his teaching). You can be in the middle of your scene and see people walking around in the background, a cell phone can ring in the middle of your line and you have to start over, or you can do an amazing take and the focus was soft so you have to do it again. You may not even be told that's why you're re-doing the take.
This is why you see the same people hired over and over, because they know how to work on set. That's why I recommend set visits so you can familiarize yourself with the pace, and the lulls.
For more tips and articles by top entertainment industry career coach, The Greenlight Coach, visit www.TheGreenlightCoachBlog.com