Who uses them and why, or what are your reasons for not using them.
My self personally I have never used one, and prefer to go into my workouts and lifts the max I can on that day regardless of what I did the week before, obviously always striving to go bigger, but don't keep a diary just go to each work out by feel and take my muscle to failure regardless.
Its something I thought about recently. The only guys ive seen using them are the typical PT's that barely look like they lift. I'm not saying there the only people using them, but is it too much of a distraction? I'm a big fan of getting in the gym go hard, get lost in focus and leave.
I understand how monitoring progression is important though, so I'm a little confused about this.