Pressure as a Concept

Many people talk about having "Good Pressure" or "Being Heavy" in jiujitsu without really thinking about what that means or why you would want it. For a while I was really obsessed with being heavier with my opponents, really crushing them down whenever I was on top. Then I realized that I got swept more often against bigger guys when I did that. Linking so much of my weight to them gave them more control over me while sacrificing my mobility advantage. Against people my size the conventional notion of pressure was fine, but against larger people I was getting too enthralled with the idea.
So I stepped back and asked myself WHY I wanted to be heavy. Why did I need "good pressure"? There turned out ot be several reasons. One was to give myself more opportunities for a submission. If I'm heavy my opponent has to work harder, has to open themselves up more, has to give me more opportunities. Another was to make my opponent tired, but again the end result of that is to give me more opportunities for a submission. To prevent my opponent from escaping, again to give myself more opportunities for submissions.
So I looked at these goals and then I looked at what I was doing and thought, "How can I accomplish these goals most efficiently?" Having good weight distribution and being heavy is one way, but it's not the only way and it's not always the best way.
As a small person I'm frequently going to run into people for whom my weight, no matter how well placed, is negligible. In those situations I can't rely on being heavy. I have to rely on other types of pressure.
To find other ways to generate those same results I thought about what pressure really means in the abstract sense. It means stress. I want to create stress in my opponent to make it harder for them to plan, harder for them to implement their game against me. I've started more and more to do that by being increasingly mobile. I'm heavy where I can be and when I can be, but I don't get committed to the idea of crushing someone with my weight. I use my agility and my mobility to continuously move and attack my opponent and keep them from implementing their game plan or being able to work against me. I keep good pressure by making my opponents react to me.

So don't get too attached to what you THINK something means, back up a step and look at what you're trying to accomplish and see what works best for you to accomplish it.
Remember, the best thing about jiujitsu is that if something works, it's good jiujitsu.