Actors and Models require a portfolio that helps represent their range of talent or looks to prospective directors. For those already working, the agent must work hard to get in front of new employers, with material they have not yet seen in hopes of finding the right “look” for the part. So that means the job of keeping a portfolio fresh, curated and ready to present never ends (unless you are retiring.) This fact is why actors and models are constantly updating their work, proving to all that they are working, active and sought after.
You can’t get all this done with ONE photographer or one very long photography session with a 10 clothing changes; you do it over time with different photographers who add new dimensions to your portfolio.
Beginning models often must work with photographers who are also learning the craft, and the goal would be to progressively weed out images that are “lesser” than the ones before. As the model or actor gets better and better work, the older work gets culled down to only the very, very best.
Model/actor portfolios should contain no more than THREE images from the same session, and only because they convey different messages. If two images look nearly the same in expression, tone or pose, then only keep the single best.