I've been doing very extensive warmups from probably second year of me working out. The best decision ever, I enjoy them now a lot, feeling how tissues become warmer, more elastic, it's a part of a workout, the most important one I dare to say.
i do many low rep warm up sets. Fuck all that jazz.
Most I see do all that shit, never look like they set foot in a gym anyway, totally not needed.
If doing as a must, are super injured, I can understand. But I see fuckers doing all that do then go do 10lbs lateral raises.
C'mon.... Get the fuck out with that shit!