Waiting until the last minute to ask the doctor something is a problematic thing to do.
Some people may be intimidated by the doctor and too embarrassed to talk about certain things. The doctor, of course, does his or her best to elicit from the patient what needs to be done. After all, a doctor uses interpersonal skills to show that he or she is just as human.
Sometimes, the fear to speak up is too strong. The worst thing that could happen is that the patient finally has the courage to bring up what he or she wanted to tell the doctor all along and does so just as the doctor is leaving the room. This is sometimes called "doorknob syndrome" because the doctor is ready to open the door when the patient speaks up.
It's a problem for both sides. The patient still doesn't get his or her real problem addressed while the doctor realizes that it's now too late to even do so. There's always a future clinic visit, but it's something important, it becomes frustrating to wait even longer.
A useful tip for patients would be to have a list of questions and issues ready before the doctor comes in. It's easier on everyone when the agenda is laid out from the start. When time is used efficiently, the doctor can surely deliver the best care possible.
