This is a question that is just as relevant in the digital era as it was in the film years. We used to think in terms of 12, 24, 36, and for the giddy professionals…70. Now people are accustomed to shooting off 400 shots before changing a card.
But the answer to the question is still the same…” about a dozen good ones “…and this indicates that you are really on a roll for a very short period of time. Either your light changes, your position changes, or your model changes. And in some cases you simply change your mind.
The trick of knowing when to shoot is even more delicate than knowing what to shoot. Real estate and landscape types know this only too well as their best shots are when the day or night is most stressful. Sports shooters take their best shots when times are desperate…and that pressure rubs off on them. They can be desperate people all the time.
For portraiture you get the best results when the subject is relaxed and approves you. In some cases that is never, and you just soldier on. Even with the good ones there is a definite time frame beyond which the subject packs up either mentally or physically, and you get no good shots. Learn to recognise the signs of sitter fatigue such as fidgeting, boredom, or slumping unconscious to the floor.
The product shooter has a longer strike period, provided the goods are not perishable. And the final shot, with all the mistakes ironed out, is the signal to strike the tent and rush to post-production. You’ll know the money shot when you see it, and it is a sign of professionalism to cut the session short when you have reached the peak.
And always remember the maths of the 35m roll of film; you get 3 good shots out of 36 and one outstanding one. Keep the three but only show the one.