Sauron's battle strategy

Lets say Sauron had adopted a Hannibal-like battle strategy & sent plundering orcs & Trolls directly to Rivendell, Loth Lorien, Orthanc & to the Grey Havens rather than to Minas Tirith. This is in line with the Battle for Middle games to make an analogy. How would Middle Earth have changed if Sauron only attacked key targets? So long as enough soldiers stayed in Mordor to protect Sauron, it is possible that Middle Earth could have been obliviated & the Ring found even before the Company could have reached Minas Tirth.