There is a phrase in lifting, everything works, but nothing works forever. When you are a beginner, all plans, workouts, exercises etc, give something, but after some point, you will see very diminished results.
Why - what is strength
There are three ways to get stronger
1. Increased muscular recruitment
2. Increased skill level
3. Increased muscular size/cross sectional torque
When you are a beginner, all three are much easier to result in the bar having more weight each week, and you feeling stronger.
How - to keep progressing
Our top three are tips are:
1. Learn how to use a belt properly (and other kit)
2. Learn how to understand intensity
3. Learn proprioception
1. Intensity - post beginner
When you start lifting, its almost a 1:1 relationship. Each workout you have sufficient training stimulus (stress) for a result (muscular growth or increase recruitment).
Once you get to a certain point, you don't have the capacity to create enough stress in a single session, and reliably recover for other sessions. This is the essence of programming, using multiple days, multiple workouts to create results.
For example, there are two trainees:
Person 1. Decides if his bench wont go up, he should train twice as hard and long on Monday, chest day
Person 2. Decides to split his volume across two days, and due to the lower workload on each day, is able to increase his intensity
Person 2 recovers better, grows better and gets stronger. Person 1 has sore elbows and is smoked before he finishes his workout.
Remember, ligaments and tendons have different recovery and stress modalities than your musculature. Many of your favourite 2000s bodybuilders trained once per week, but ah, they used lots of stuff. Many of your favourite 80s and 90s bodybuilder hit muscles multiple times a week (Arny was famous for doing chest twice a day, so he could train it harder).
2. Use Belts and Equipment well
A belt creates intra abdominal pressure, that pressure helps the spine deal with the high shear stress its suffering during lifts.
A squat, with a bar on top of your shoulders, and the highest weight possible may not be the most natural function of the body. Given this, supporting your body correctly is key (doing it poorly is almost useless).
Put your belt on - put your thumbs in the belt, and push out till you crush your thumbs. If you can to that, you have created intra abdominal pressure.
This applies to all lifts where you can be more safe. If you have bad shoulder mobility and your wrists roll back when you squat, wear wrist wraps. If your wrists are weaker (because you have genetically small wrists or a injury) - wrap your wrist while you bench etc.
If your grip gives out on rep deadlifts, where straps. There is no prize for injuring yourself when one hand lets go. If you want to train grip, set up the bar at lockout - and train it effectively.
3. Pay attention to your elbows and knees
This is one where some people need no time on this (ie, naturally sporty people) and some people need lots and lots of time.
When at the gym and teach people to bench, squat or deadlift, it would amaze me that one knee would be angled out, the other in and the trainee didn't notice anything. If you continue to lift like this, you will get injured (and by function, not get stronger).
Squat in front of a mirror, film yourself, ask people to watch, whatever feedback loop you need for your knees and elbows to follow the same path. Make sure feet line up, at the same angle etc when you squat and deadlift.
Thats 3 easy ones! get after it, and get stronger