Complex sentence: Generally, people work not as isolated individuals but as members of teams and organizations, and it is sometimes important or necessary to shift the focus of human-factors analysis from the individual decision-maker or actor to the whole team.
Split into simpler sentences: Generally, people work not as isolated individuals but as members of teams and organizations. It is sometimes important or necessary, therefore, to shift the focus of human-factors analysis from the individual decision-maker or actor to the whole team.