A question about the code

[Cspicp]

In FaceDetectorAndTracker.cpp
void FaceDetectorAndTracker::track()

	if (m_faceTemplates[i].cols <= 1 || m_faceTemplates[i].rows <= 1)  
	{
		m_facesRects.clear();
		m_tracking = false;
		return;
	}

I want to know why the figure is 1, and is it based on experience?
When I delete this statement and tried to remove one of the detected face from the frame, there will be some delay.
When I change the figure into 2 or 3, there also will be some delay, and soemtimes the two face even couldn't swap (although they are of proper size).

Hope for answer sincerely!!!!