When I was a TA at CMU, we used Gradescope https://www.gradescope.com/ https://www.gradescope.com/ for this. Every exam would be scanned and divided into proble

When I was a TA at CMU, we used Gradescope https://www.gradescope.com/ https://www.gradescope.com/ for this. Every exam would be scanned and divided into problems (based on a predefined template - fixed page space for answers). Then, each problem was assigned to a TA. Either there's a predefined rubric, or you create it as you go (-1 point for mistake X, half credit for mistake Y, etc.). There's a pretty slick interface where you just read the answer, and use keyboard shortcuts to apply the relevant deductions. It still has the issue that every time you change the rubric, you'd need to go back and re-do previously-graded instances of that problem. But it was way faster and (equally important) less tiring.