Ok, stop getting so confused with the details. There are two ways to get big, and you can combine both.
You need to add up to 600-500 seconds of T.U.T: for each muscle group, in a weekly cycle. If you take a good look at GVT, you get 6 seconds of T.U.T. per rep, and do 100 reps once a week for each bodypart. For arms, you use a tempo of 302, hence, a 5-second T.U.T. per rep.
Use the Timed Sets. Train 3 times a week, using 5-7 sets of 20-40 seconds per session ( you are adding up to 200 seconds per session more or less) and adding up to 600-500 seconds of TUT per week. One small thing: let the load tell you how fast you should move, so any tempo can be good between X0X and 20X.
After using this method for 3 weeks, move on to Isometric/Dynamic contrast. Simply do sets of 10 reps, using a 20X tempo, with a twist: at the middle of the negative phase, take a pause. The first paused rep should have a pause of 10 seconds, and the last paused rep a pause no less than 2. Only 1 out of 2 reps has a pause, so alternate between normal reps and paused reps.
Each set will get you a TUT of 50-60 seconds. Perform 12-15 sets per week, in 2 or 3 sessions. I would only recommend 10-12 sets at best, even only 8 for hardgainers or skinny guys, since 12-15 is more suited for people who have some fat and want lean body mass gains.
Also, for both of the emthods, Timed Sets and Isometric/Dynamic contrast, you should rest 60 seconds between sets, even down to 30 in the Timed Sets for people who are interested in burnign some fat.