My form is an assessment of a process that has a number of stages. I would like to be able to grade each stage of the process individually, as well as develop a grade for the overall process.
My form is made up of many different field types, including quiz fields. The sum of the quiz fields will, I hope, produce a score and a grade (still building the form) but I don’t know if it is possible - and if yes, how - to grade each stage of the process as well.
That sounds like a great project. Regarding dividing the quiz into sections - The Gravity Flow User Input step lets you define a subset of the overall fields in a form which a user (step assignee) gets to see/edit at one time. It might make a great part of your overall solution.
I haven’t personally seen any solutions that do automated grading for Gravity Forms but I wouldn’t be surprised if some are out there. If you aren’t afraid to look at code-based solutions, gform_after_submission and the GFAPI would let you update the entry post-submission. gravityflow_step_complete provides similar that can be customized at the end of each step.