It is easy to think, when you start writing that you should describe your characters in detail as they arrive in the story for the first time. But why would you want to stop the story for a large wad of description, however beautiful it might be. It isn't a film, where the visual of the character often hits you before they utter a single word.
Before I say another word I would like to make it clear that I am firmly in the camp that says there are no absolute rules when writing. There are 'guidelines' that help and 'suggestions' as to technique but as soon as someone declares something to be a 'rule' a dozen well-qualified voices will shout that they do it differently!
But in a book the person behind the visual is more often what the author is trying to portray and as such their appearance is not necessarily noteworthy except on the occasion that it furthers the plot or your understanding of the character and their situation. So it follows that you can drip feed in this information as and when it is needed and in small slivers that enhance, rather than indigestible lumps.
As a reader, when you are engrossed in a book and get to know the characters well - unless their appearance is important to them or so strange that people in the story stop to stare - you may discover that you don't actually recall whether they have long or short, blonde or black hair, or if they are tall, short, thin or fat. That is because you know what is in their heads, how they think, what they care about and what they will do in any situation.
? What did you actually see ?
Perhaps it is the same as a policeman taking witness statements after a bank robbery. Often the witness statements vary so much that it is almost impossible to to get a real picture of what the criminals looked like. But the witnesses will probably be able to tell if one of the bank robbers was violent or spoke aggressively.
Most of us have times when we meet people but cannot recall their names or put a name to a face but the temperament general disposition of that person is more likely to linger in our memory. How often have you failed to recall someone's name, or whether a person wears glasses or has a moustache.
How much description do you prefer? Do you agree that often, when it comes to describing a character's appearance, less is more?