Perhaps. as with all flying exercises, it is more easy to understand what you are doing and trying to achieve If you discuss what the actually AIM of the exercise is.
Can I remind instructors that the exercise is not a trial lesson, it is AIR EXPERIENCE. Try briefing yourselves on what you are trying to achieve and what you want the student to leave the school having learnt.
Below I have listed some of the aims i have come across with this exercise.
To keep the flying school in business
To build up hours
To give a PPL free flying
To show off your flying skills
To chat up a student
To ferry an aircraft
To do a weather check
My aim is the one I write on the board
To introduce the student to the sensation of flying in a light aircraft.
Can that aim be achieved at Night, of course but can it be better achieved during the day,unless of course you intend to conduct the whole course at night.
Taken to its extreme its a bit like saying, should you do a Ex 3 in a thunderstorm? Of course you should if you intend to conduct the whole course in a thunderstorm!