1) Managing multiple websites requires setting up tracking and analytics properly across websites using Google Analytics and Google Tag Manager best practices. 2) GTM allows for flexible and fast tracking of everything across websites using one master GTM container exported and imported to other containers. 3) Custom alerts and dashboards in GA help monitor website performance daily and weekly. 4) Automating reporting with spreadsheet reports connected to GA via APIs and scheduled sending reduces work and ensures timely insights. 5) Coordinating websites takes some project management, communication, and keeping the overall picture in view.