That's exactly what it says in the example. Holy shit 10 sets! But really its not a whole lot. You take a minute or a minute and a half in between sets and its 15minutes. You'll lift more (typically) and be better prepared for the working sets.
Its not that a longer warmup improves performance, its the procedure you use that gives you the performance. You could do 10 sets of 5 as your warmup and do it in the exact same time as the one I posted, would your working sets be improved? A very big NO is the answer.
A proper warmup involves warming up the muscles involved, lubricating joints and preparing your for the training environment to come (read: acclimation
). Time is not a primary factor of a warmup's effectiveness, although it is at play.
For me, my warmup is dictated by the exercise I'm warming up for. Smaller weight exercises (bench, MP, cleans, etc) are tightly spaced, weight wise, and typically need a bit more acclimation (ie. more warmup singles, >10sets total). With my heavier exercises (Squat, deadlift, etc.) I can stick to the 10 sets with big jumps in weight and be better off. Its something that needs to be tailored to the individual, just like diet, training and anything else lol.
BUT you need to start with something before you can manipulate it and make it your own.