There are a few things that are important to stimulate muscle growth. Intensity is important. This can be in terms of mechanical stress/load/weight lifted. There are also techniques that focus more on metabolic stress such as high reps, drop sets and other techniques that can cause temporary occlusion to muscles worked.
I incorporate both and the objective is to gradually increase intensity, total weight lifted and total volume of training over time.
I explain in more detail in the video, which was filmed a few months ago as part of my 8 week cut video tutorial series.