I've taught a lot of programming courses that have 20:1 or even lower ratios.
I always use automated grading to check for correctness. That way I can give more attention to other aspects of the grading rubric (a bit of style, but most of the time just understanding the thing we're supposed to be learning -- pointers, for loops, specific data structures, etc.)
For smaller programming assignments, you need to check that the right language constructs are used in the right way. E.g., you really have to go in and read to program to be certain that students are using for loops correctly. Just because the code outputs the correct answer and uses the "for" keyword, doesn't mean that the student understands how to use a for loop. I don't think it's possible to automate this check.
Similarly, it would be insane to grade a large programming assignment based on test cases alone because a) "program design" is a major part of the assignment and b) it'd be impossible to get full coverage without an insane amount of work.
I think it's a bad idea to not use automated grading, even in 20:1 classes. But of course you should also be reading the code and commenting on it.
I always use automated grading to check for correctness. That way I can give more attention to other aspects of the grading rubric (a bit of style, but most of the time just understanding the thing we're supposed to be learning -- pointers, for loops, specific data structures, etc.)
For smaller programming assignments, you need to check that the right language constructs are used in the right way. E.g., you really have to go in and read to program to be certain that students are using for loops correctly. Just because the code outputs the correct answer and uses the "for" keyword, doesn't mean that the student understands how to use a for loop. I don't think it's possible to automate this check.
Similarly, it would be insane to grade a large programming assignment based on test cases alone because a) "program design" is a major part of the assignment and b) it'd be impossible to get full coverage without an insane amount of work.
I think it's a bad idea to not use automated grading, even in 20:1 classes. But of course you should also be reading the code and commenting on it.