The way the VA math works is that one catastrophic condition can lead to a 100% rating. You can also get the cumulative value of several lesser issues, but regardless of how bad or how many issues, the largest payment you get is 100%. So it's not really an indication of your disability or ability at all, it's just a tally of your compensation. As mentioned, other systems try to rate your ability to work which is actually pretty hard to do accurately.