Some people say it does not matter – the reader wouldn’t see the difference anyway. That might be true – however good kerning is a skill and good type designers include their specific kerning into their fonts. Now this is only of use, if the graphic designer, who buys and uses these fonts also knows how to access them.
It’s only one click – preferably in the character styles – that can change the layout of a whole book if you do it at the end. So knowing it in the beginning really saves you time.
In InDesign you can choose between metric and optical kerning (bottom left in each window)
Metrics chooses the kerning, which the type designer has established in the font.
Optical is based on an automatic kerning defined by InDesign
So if you use a quality font, then metrics is the setting for bigger amounts of text and long paragraphs. Thorough typographers often also ‘hand-kern’ headlines.
Below are the options Metrics, Optical and zero compared: