Tom Platz is one of my heros. Amazing mind. Remember that he had one of the best set of legs in BB. You have to keep in mind that what worked for him...and what works for any genetic freak, may not work for everyone else. I imagine that he needed some serious rest after his workouts because he was an artist and over years, learned how to increase the intensity to such a level that it was/is far and above most peoples abilities. Intensity is something that we learn to craft over time. 

So instead of focusing on the number of sets, focus on the intensity. Learn to make the sets HARD. Take the weight you're using and get the most out of it. Keep working on the perfect form and movement to put the most pressure you can on the muscle you are intending to work. Then do what it takes, killing each set, Then from there, see how long it takes you to recover from your workout. Everyone recovers at a different speed. And remember, your nutrition plays a huge role. I find that if someone really works hard, most people can recover in several days to a week and be strong enough to go hard again. 

I've had back issues on and off, so I haven't been able to always destroy my legs with heavy weight and high reps, the way I'd like. So I find that if I split hams and quads up, training legs 2x wk, I am able to bring more intensity each wk, by training legs in 2 sessions. I find that for a lot of guys that need better legs, splitting them up into 2 sessions works well.