It’s awkwardly written but I imagine it’s the difference between “I consent to this at an undefined but bounded time in the future” vs “I consent to this right now or at this predetermined single moment in time”.
Alternatively it could be “exams that would previously been non-consensual.”
Surgery can have complications, so the patient may be under anesthesia longer than originally planned delaying the practice exam.
Not meaningfully in a first past the post vote. Ranked choice or some other alternative, then sure…