triplesix, I've tried 5 X 5, DC, and other various programs out there and while HST may not work for all,..it certainly works for me. Its all based on very solid hypertrophic principals, so if your goal is to add mass,..certainly give it a shot.
On my 3 HST cycle now did first two a year or so ago, then tried 5 X 5, & DC, then went to a Westside Routine for 10 weeks. Now back on HST. Westside is actually very similar to HST in its hypertrophic effects in a lot of ways.
For me what works and what I'll be continuing with is cycling back and forth between HST and Westside every 6 months or so.
After taking some time off from lifting and starting back up a few years ago my bis went from around 15 3/4 to a now just over 18 inches. Back has a ton more mass (especially on HST) and overall body has kept right along with Bi growth.
Only thing you really need to change on the HST program in my opinion if you're an experienced lifter is the "Eating or size" portion of it. I really needed to up the calories on that part for adding mass.
36 yrs old now, 6'3" weight at 220 w/ 14% BF & all natural