How much effort should I put in to optimizing (cutting up) images for the web

How much effort should I put in to optimizing (cutting up) images for the web Graphic Design Stack is a question and answer site for Graphic Design professionals, students, and enthusiasts.

Answers of How much effort should I put in to optimizing (cutting up) images for the web? A successful graphic designer has the mentality of a problem-solver. Problem-solving is about finding the issues, understanding them