Hah! Sorry for the cheesy headline, the more appropriate headline is: "The biggest mistake people make with HST." And, I'm sure this was discussed multiple times (so feel free to ignore), but I was thinking about it after revisiting the site off and on over the years (started in 2002, I think). So, I might be saying the same thing that everyone has already agreed on, but just thinking out loud, so I went ahead and typed it. Short version: Make sure you are still increasing your rep maxes. Medium version, summary of my guesses and assumptions (some likely wrong): Skip SD until you actually need it. SD and the usual HST progression helps with adding size, with the least amount of weight, but the weight still has to increase over time. For significant size increases, a significant increase in the weight on the bar will still need to occur. Repeating previous workouts after SD does cause adaptations in the muscle. I think every weightlifting program has deloading, so I don’t know why SD is such a sticking point for some people. But, perhaps SD is used too frequently for beginners and RBE is probably overemphasized for this same group. Or, actually ignore all of the above and keep SD after every cycle, but make sure you consistently increase your RMs throughout the year. At some point, increasing the load slows way down, so look at adding more frequency or volume (more sets or more exercises per muscle group). Long version (full of my assumptions): People (or what I was initially thinking) get to HST principal number 4, remembers to train often enough (Principal 2), but then forgets number 1 and 3 in the bigger picture by ignoring progressive overload from cycle to cycle (or every other cycle). SD doesn't decondition us enough to just repeatedly recycle the cycle and get exponentially more muscle. It initially adds some hypertrophy, but with diminishing returns. Perhaps repeating 2 or 3 cycles would get the most muscle/hypertrophy out of that same RM weight on the bar, but I don’t have a clue. That approach would minimize injury risk and be easier to do. So, is SD good for beginners (or even intermediates)? I'm guessing that it's not actually needed for a while and it's probably better to delay it as long as possible until you can’t continue to add weight to the bar on the different rep ranges of 15/10/5 (or if still progressing, just wait until it happens with work/vacation, etc). Is SD good for experienced lifters? Yes, but maybe try doing back to back cycles before SD. Side topic: I think that it would be good to note if you progress better on certain rep ranges. If it’s easier to progressively add more weight to the bar in the 10s, than I think it would make sense to do a longer mesocycle of the 10s. Or, just jump directly back into that range immediately after the 5s, and run with the 10s for a while. I assume someone progressing in that range, and then getting close to weights in the 10s that they used to be doing with the 5s, would be adding more muscle. And, counter to that, maybe focus on the rep range you suck at for a while until those get more in line with the other rep ranges (percentage-wise). That's another assumption: A lifter that is stronger throughout all of the rep ranges is generally going to be bigger. At the very least, skipping SD, and repeating cycles with incremental weight increases, chases the strength gains quicker. Does anyone complain that they are too strong? And perhaps these strength increases later leads to larger muscle growth after SD. So, I think to "optimize" for growth, a lifter needs to make sure they increase the weights on each successive cycle. Oh, duh, that's basically 2 of the 4 HST principals. Great insight by me (sarcasm). As an example, because I’m rambling: Take a beginner (and I’m ignoring doing the negatives after the 5s): Starting with a 15RM of 135 lbs for back squat. Unless they have severe recovery issues, I’m assuming someone doing that weight should be able to easily add 15 pounds to their next RM for squat, that's in 6 weeks (if my math is correct), and only 150 pounds. Surely a normal trainer can squat 150 x 15 after doing the 6 workouts working up to 15x135, and the 10s and 5s. Plus, the other 5 workouts of the 15s before the workout with the “new” 15RM. Correct? So, why not skip SD while those strength gains are readily available? Simply adding 15 pounds to the squat every cycle should be quite feasible, at least initially. That equates to a smaller percentage increase on each progressive cycle, so it builds in that gains slow as the lifter progresses, vs. simply adding 10% more each cycle. Or, take a more conservative progression of 10 pounds per cycle (every 6 weeks). But, after a year, and two SDs (say, one at month 5 when gains slowed, but then one 3 months later (at month 8) because the gains started to slow down sooner), that trainer has knocked out (assuming 52 weeks in a year) 49 weeks of training. That’s slightly more than 8 cycles (6 weeks each) over the year. So, that’s 80 pounds to a 15RM squat. Not a huge number, but I think it’s safe to assume someone that can squat 215 lbs for a set of 15 is going to be bigger than they were a year prior when they were maxing at 135. I also assume if that same lifter was increasing 20 pounds every cycle (every 6 weeks), would be adding considerably more strength and muscle over that same time frame, because they've progressively worked up to that number. Of course, a 295 pound squat at 15 reps sounds pretty impressive. So, maybe more realistically, those numbers increase 20 pounds the first 3 cycles, then 10 pounds per cycle after that. I also wonder if people are overvaluing RBE. Yes, this plays a role in preventing added muscle growth, but you see people that train consistently for 9+ months, and they’ve made considerable progress. And, dang it, I forgot about the study on trainers taking 3 weeks off, every 6 weeks, and getting similar results as the group that was training consistently that whole time. So, sorry it’s taken a full page of rambling to say that SD is fine to take, even for beginners, BUT make sure you are increasing the weight cycle to cycle (or even every other cycle if you want to play it safer/easier to do). So, maybe worded a different way: increase the mechanical load (HST Principal 1). The other principals are there to help optimize and manage that increase.