Every practice I've worked in or been in as a medical student is almost the complete opposite of what you described. Yes, the physicians can have some influence over their schedule, but the organizations set minimum numbers of appointments which results in truncated appointment times with an extra hour or so at the end of the day to finish all the notes. And even if the physician has control over how the schedule is made, that cannot account for other patients being late, or appointments taking longer than scheduled because of serious discussions or problems that need to be addressed, or the physician getting pulled away for urgent consults or messages.

As a patient, I would rather have a physician that runs late on appointments because they give the patients as much time as they need as opposed to a provider that is perfectly punctual and makes you schedule another appointment or punts you for anything that exceeds the slotted time.