I developed my knee shield when I was a blue belt. I've spent a lot of time on it. Just keep practicing.
Holt and I aren't big guys. I'm around 140. Like he mentioned, it's a very effective guard to used against big dudes and keeps their weight off of you and allows you to work.
If I can't get anything going with my knee shield then I will transition. It's always on a case by case basis. It depends on what the guy is giving me, what I'm trying to work, or even how tired I am.
What do you mean by "mule kick"?
Nice. I'm about 1 year into my blue. The mule kick is just what my brain says when it happens. They either leg weave or grab my pants at the hip and power sprawl or kick to remove my hooked bottom leg. Then they just run around and pass. I've never really found a solution. I've tried doing the leg lasso when they weave, but sometimes it's hard if they are ready for it. Any tips?