You should get all S ranks no problem!
There was only a few levels levels which took more than one go. Main thing is not dieing, and just do it fast, only really seems to go off time and not dieing as rings don't add many extra points.
Getting 1000 was slightly tedious with all the challenges that you have to do, again most were very easy (grade doesn't matter on them) only one or two I had to have more than one go on.