As for the "cutting phase" and supersets and drop sets etc is not how you get "cut" or lean, or how to bring up vascularity and definition. Thats all diet period, if your diet is not clean and your not in a deficit of calories you will not get lean vascular or cut. Whats holding you back from bringing out definition is the layer of fat over the muscle, the only way to get rid of that is by dieting and losing fat. The high rep ranges have nothing to do with it, 8-15 is reallly the true muscle building rep range for most people. The supersets, dropsets circuits etc wont bring out definition or the it unless youre diet is right. If your diet is right then the high intensity workouts will burn more calories then a traditional workout. As for vascularity i think there is two things that effect it, the first being time, when i started i had no veins anywhere, over time more and more came, then they started getting thicker and thicker and still to this day new veins pop up, babies at first then they grow thicker. The second is genetics. No matter what I do, use wet compounds high carbs big bulks and bf climbing up im always still very very vascular while the next guy loses alot of his vascularity when his bf gets high, he retains water etc. Just like some people have really full and well shaped muscle bellies, or other different strong points I think vascularity is also very genetic.

As for the rest of it i like the periodizaton, at first as a newbie the gains just kinda come if youre eating right, you can lift in the the 8-12 rep range and just get bigger and stronger fast. Once your past the beginner phase staying in the 8-15 rep ranges will cause you to stall as strength gains are pretty slow in that range and its hard to keep building muscle if youre not adding reps or pounds to the bar each week. So its good take 4-5 weeks every so often to lift purely for strength and then bring that new strength back to the muscle building rep ranges and apply it to building new muscle since you can lift heavier. I do something similar myself, but without any set plans. Ill keep the reps between 8-15 for as long as im getting bigger and when that stalls after trying to swtich routines and such ill spend a few weeks in the 4-6 rep range focusing on just getting stronger, longer rest periods, less reps and sets, less days in the gym etc. training like a powerlifter basically. But its not only strength i gain, its a big shock to the muscles after lifting in the higher rep ranges for so long so ill add some muscle while gaining new strength. Then after a month or so ill go back to the bodybuilding style training and start progressing again.

It sounds like you're moving from strength to hypertrophy to endurance. I personally see much better results from going the other way around. To maintain an aesthetic look while doing this, I just keep the rest short and the TUT long. Example:

Phase 1:

Muscular endurance-
Circut A- quad Dom
Back squat 3010 tempo X 10 rep
Rest :10
Leg press 2010 tempo X 12 reps
Rest :10
Leg extension 10X0 tempo X 15 reps
Rest 3:00 before repeating total 3 times

Phase 2:

Hypertrophy

Squat 40X0 tempo X 8 reps
Rest :30
Ham curl 50X0 tempo X 8 reps
Rest 1:00
X4 sets

Phase 3:

Strength-

Push the tempo up to 5 seconds (although sometime I drop the tempo to push more weight) on the eccentric; keep rest to 2-3 mins only- depending on reps. 2 mins for 5s, 3 mins for 3s. Up to 4-5 mins for heavy singles. Only focusing on one exercise at a time.

Again this is just an example of the type of stuff that works for me. There are many ways to skin a cat. Each person will have something that works for them. Experiment and find what works for you! Lastly, none of this stuff even matters in the slightest if diet is off. Hope that was helpful. Happy growing bro