Why every pages analysis is not available in Google analytics?

GA script should trigger events every time you load a page with a snippet on it. In case you don't see data for specific pages - try debugging it by opening the page a few times yourself or even opening a Network tab in your browser and looking for "collect" requests. If this doesn't happen - your snippet is either absent, the trigger is not set up or the property / view you've set up in GA has this page excluded from reporting.