Your replays really helped, thanks! To answer your question, I usually only do mounts or guards in two situations. Situation one is that I'm getting lifted, so I use my arms and pecs to swing a leg around and hook into a mount. Situation two if for pin pressure, half guard and pin pressure are very effective against suplexes and half/full throws. I'll attach an example of each.
Make sure you pause the replays and press E at key points to see what joints are doing what, that helps me a lot