Been training 1.5 years now with no competition goals in mind, just like being strong. Jumped into 5/3/1 after my Starting Strength gains subsided. However, I did not take the "traditional" approach with training - being that all of my squatting has been box squatting and I have an approximate 1RM of about 410. I tried making it work but at 6'5" I am guessing my lever lengths have something to do with my issues. I simply can't go anywhere near parallel. Tried YouTubing mobility drills, etc. Did the Agile 8 4 times a day (yes, 4. Once in the morning, once at night, and twice on break at work.) Nothing. Anyway, the point of this post. I did some reading and 'old school bodybuilders' used to put a 2x4 under their heels to hit perfect depth. Tried it, and what do you know? My hamstrings ended up touching my calves. ATG full squat with no issues whatsoever. My questions: 1) Is it safe to continue doing this? 2) If not, what is it about raising the heels that enables me to hit a proper depth squat?