In my university professors often allow only one-two students at a time to enter in their office to see the corrected exams in front of him/her. So the students can ask some question but not allowed to leave with the orginal sheets.

The clear drawback is the time consuming management of the "review day" but for sure you will not have that problem anymore and (from my personal point of view as student) students are more encouraged to ask questions about errors.

In my university professors often publish the solution right after the exam.

Then, they establish a "review day" in which only one-two students at a time are allowed to enter the professor's office to see the corrected exams in front of him/her.

In this way students can ask some questions but not allowed to leave with the orginal sheets.

The clear drawback is the time consuming management of the "review day" but for sure you will not have that problem anymore and (from my personal point of view as student) students are more encouraged to ask questions about errors.