I do both. It really just depends on what Im feeling that day. I am not one of those guys that strolls into the gym and has their whole workout written down on paper. Fuck that. that way you are telling yourself what your body is going to do. I do what my body tells my mind to do. Whatever my body feels like doing whether its deadlifts, smith machine shrugs, dumbells...thats what I do. Ive found that I am more prone to injury when I do excersieses my body doesnt feel like doing. So to answer your question, I both. It just depends on what Im feeling that day. Think about it, if you need to do barbell presses but you dont feel like doing them...how hard to you think your going to hit that excersies, as appose to finding something that you feel like doing. thats just my own personal thoughts and how I train.