Intensity is a very important factor. Perfect form and routines do not build muscle. They are good to know, but to make any significant gains you also have to push yourself hard. You need to put intensity and aggression into your lifting. Be determined, be focused. Put your max effort into every rep (after you've done your warm up). Even if you are doing lighter weights, try to move the weight as fast as possible. Don't be afraid of failure. Keep adding more weight each week until you fail (with safety). Believe you can lift more. I've been lifting for off and on for 15 years, weigh 160, bench 325, deadlift 425 while spending just 1 to 3 hours per week in the gym. Most of my recent strength gains came after watching videos of Louie Simmons and Westside Barbell. Spend only 30 minutes in the gym, but work your ass off for those 30 minutes. Generally I work each muscle group one time per week. If I want to make serious gains, I'll work to same muscle group two days in a row, then rest that group for 6 days, and repeat. Pre and post-workout Celltech, or creatine and sugar help to make gains, as well as whey. If you want to build muscle, join a gym with serious lifters. I always work out harder when there are serious lifters in the gym, competitive pressure. The Planet Fitness commercials make me laugh because the guys they make fun are clearly experts in lifting, but instead of wanting to learn something from them, they ban them. Get you burn on bro! https://www.youtube.com/watch?v=Rn5mzEAMAkY