I also agree that you're never likely to get asked, however if you get them all first time it is good to be able to mention that on your CV. It might go un-noticed, but anything you can do to make you stand out is worth doing. I'm not a good case study as I don't have a flying job (!) but it might make a difference to somebody looking at you.
I was planning to just aim for a pass in all mine but when I was in the admin office of my groundschool provider, I happened to notice some results info sitting on the desk. It was for some sponsored cadets and some of the people were getting 100% across a large number of the subjects - the rest in the high 90s.
It was then that I decided to reduce the number of papers I was attempting at each sitting and to aim for the highest marks I could get as I wanted to look as good as I could against these guys.
I averaged 89% but out of all the application forms I've filled in, only one asked.
All the best..