Can i leave admin rights in a session?
There might be a way to modify the standard behaviour by doing some fancy low-level unixy stuff like creating the "root" account and logging in as that which would cause the authentication dialogues to not be so intrusive, but for the average user, the answer is "no".

A non-administrator account will be presented with an authentication dialogue in some situations where an administrator account would not have been presented one (such as when modifying items in the /Applications folder), so perhaps doing system updates might be easier when logged in as an administrator. You can change any non-administrator account into an administrator account by selecting the “Allow user to administer this computer” box in the “System Preferences” -> “Users &amp; Groups” settings window.