I've had people squat 10X10's (GVT) at certain short periods of 6-8 weeks with outstanding results. Some would SS these with calf raises or leg curls. And a few would tri set them all. These would be for special needs; lagging lower body strength, stamina & development. And again, for short intense periods of time only, doing legs twice a week. . Their athletic preformances always improved during these off season programs. Usually their one rep max squat shot up greatly. Many also tried the 7X7 method, which have given me excellent results in the past with regards to quad/leg improvement.
For regular quad workouts, if you can't work the quads close to their max with-in 3 to 6 sets for max growth potentional, your not training intense enought. Too much rest between sets and exercises will not take advange of the full growth potentional correct preformance can offer. Why sholud the quads have to take a hell of a beating when more work can be done with less sets and time involved? You want just enought of a work load put upon the quads for future growth, not something that is going to put limits on the CNS and it's ability to recover. Another reason that going to failure on a regular bases should be avoided in any set of exercises. Failure can be included now and then in a workout but only on the last set of a exercise.
Gaging the quality of a workout by the amount of soreness felt has nothing to do with potentional muscular growth gained from that workout, for the most part. Soreness (pain/discomfort) is what it is. Doesn't mean that the exercise that made you sore is a great muscle producing exercise, it just made you sore as hell. For the most part, soreness has just directed the attention to what part of the body/muscle group has been worked hard. Good Luck.