You don't want to be that guy who looks like he only trains above the waist. That's why this workout is so important. Your legs will take a beating, particularly in the finishing giant set. This giant set does require a lot of equipment, so if you need to make modifications, you can.
For example, if you don't have a hack-squat machine available, grab a pair of dumbbells and do squats with them instead. If the gym is packed and you can't get to the hamstring-curl machine, lie face-down on a bench, place a dumbbell between your ankles, and curl your legs up as far as possible without lifting your quads off the pad.
Once you've achieved full contraction, lower your legs down to the starting position.
If you can't use all four pieces of equipment, look for suitable substitutes, or perform straight sets with short rests.