>at least enough to help readers visualise the scene, and so they're not caught out later. How many of us have got two thirds of the way through a book without realising a character has a beard, or imagining them with a different hair colour, before the author describes them. That's not ideal.

If an aspect of their appearance is important, I want to introduce it reasonably early. But not every character needs an in-depth description of every part of them. It's a balance.