Hello Water Dragon,
I did Judo many years ago under a guy named Lou Moyerman. I enjoyed it very much. Although when I did compete I usually got into trouble as I liked to throw someone and then step back so they could get up, I hated the ground. I did find that the Judges did not let that last very long and I was forced to do groundwork if I wanted to win. Still I never really liked the ground game.
I would agree with almost all of your post. It is always a good idea to be versatile and well rounded, again you need a solid foundation of something to build on first. It really comes down to why you are training and what type of opponent you are likely to face. Someone in a tropical climate would likely face a different situation than someone in an artic area. Thus, each would have a different focus as both environment and clothing would come into play.
The only thing I would be cautious about is the idea of having 30 seconds or more in a real fight to accomplish a specific goal. I mean 30 seconds can be a lifetime in some situations.
All the best.