This can occur, for instance, during the 30-minute period following a time allocation motion. A very quick question may be asked, followed by a brief answer, and then back. So, there is no time, really, to simply cover the member who is speaking. That is where you would use a wider shot.
The same applies in evening debates, for instance when the leader of the opposition asks for a special debate to be held in the evening on budgetary matters. There can, from time to time, be rapid exchanges between members.
That is done to ensure that, at the very least, the member speaking is seen on camera. We would not want to miss that opportunity.