Nearly every person who has ever lifted starts out by lifting for 3 sets of 10 reps on an exercise. From a brand new lifter who has never been in a gym before, or seasoned lifters when adding a new exercise. There is no shame whatsoever in this approach, but as you become accustomed to lifting weights you need to move off this basic range. For at least some of your workout, and most often, for the majority of your workout.
I see programs on the internet ALL THE TIME that are geared towards intermediate to advanced lifters and call for numerous exercises with 3 sets of 10 reps. These programs are shit and whomever is writing them probably doesn’t know what the hell they are talking about. And if that person is VERY fit, it is very unlikely they follow the program they posted.
Strength
1-5 reps. This really becomes the base you must build if you ever want to get serious about performance and appearance. Everything starts with strength, and increasing your Maximal strength must be a priority. Now this doesn’t mean trying to set a personal best of the 1 rep max every workout. That is what the 1-5 rep range is for. Dedicate 1 exercise per workout to the 3-5 rep range and you are golden. Or at least do this 1 time per week unless you are on a periodized program that has specific strength phases. In that case you will have multiple workouts per week that include a 1-5 rep range exercise, for multiple weeks. Followed by weeks where you may not have any strength rep ranges.
Whatever bucket you may fall into is fine, just do not fall into the bucket where you are never doing 1-5 rep ranges.
Strength and Hypertrophy
6-8 reps. If the 1-5 range is the Meat, 6-8 reps is the Potatoes. This range is really a blend of Strength and Hypertrophy and is something you can literally have included every single time you goto the gym for a lifting session. At this rep range the weight will be challenging enough to build strength, but have enough reps and time under tension to build muscle as well. It will not build strength quite as well on its own as the 1-5 range, and its not a pure muscle building range due to the below range having more time under tension, but it really is a 2 birds, 1 stone rep range.
A person could go to the gym and do 3 working set exercises, (exercises that count, and you measure progress against) and only do sets of 6-8 reps forever. They would continue to progress if only doing this rep range more than any other.
Hypertrophy
9-12 Reps. Hypertrophy means muscle gain, so I assume that is among the biggest reasons we see so many programs that have X sets for 10 reps. Which is fine at the beginning of your weight training journey. Or also fine as exercises after strength exercises. The problem becomes this, when you ONLY do workouts in this rep range, you will not get stronger. Meaning you will end up lifting the same exact weight, for the same number of reps. There is no progression. Progress will absolutely stall. Peformance will decrease. You will become disatisfied. You will quit working out.
This rep range is not a fail on its own. It is a fail when it is the only rep range used by the trainee. When blended in with a 1-5 rep range exercise, and a 6-8 rep range exercise, adding in one or two Hypertrophy exercises beomes MUCH more effective.
If you do only this rep range you will get bored, and quit training altogether. If you have been doing ony this rep range for a while, I would completely remove it for a period of time. Branch out and use the other three rep ranges and come back to this after a while. And even then add it in sparingly if it was the only range you have ever used.
Hypertrophy and Muscle Endurance
13-20 Reps. I much prefer this rep range to the 9-12 reps. This will also build hypertrophy, but also builds muscle endurance which has a ton of applications. Most of my workouts call for an exercise in the first two rep ranges, meaning I am using fairly heavy weights. So for a hypertrophy exercise I prefer weights where I can get to 20 reps fully rested. I also find this rep range has more athletic applications than 9-12 reps as you are training your muscles to work for longer stretches at a time, especially when you get near 20 reps.
Very basic Program Design
Based on these 4 buckets you can build an extremely effective program. Four exercises of working sets can be difficult to fit into an hour, so the most realistic approach would be to select 3 of the four buckets and go from there.
Example 1: Strength Focused
3 sets of Strength (1-5 reps per set)
3 sets of Strength/Hypertrophy (6-8 reps per set)
3 sets of Hypertrophy or Hypertrophy/Muscle Endurance (9-12 reps, or 13-20 reps)
Example 2: Hypertrophy Focused
3 sets of Strength/Hypertrophy (6-8 reps per set)
3 sets of Hypertrophy (9-12 reps)
3 sets Hypertrophy/Muscle Endurance (13-20 reps)
The first example is a damn good program design and something you can do all the time, forever. Just mix up the exercises you do, especially for Strength, and you will attain progress forever.
Bad Example: This is the crap you will typically see online
3 sets of Hypertrophy (9-12 reps)
3 sets of Hypertrophy (9-12 reps)
3 sets of Hypertrophy (9-12 reps)
3 sets Hypertrophy/Muscle Endurance (13-20 reps)
I could go on and on and on about how much I hate this type of workout. If you are working through an injury, or any other kind of health risk, then it’s fine. But if you are healthy, and looking to improve, this program will stall out before you even start.