Sauron should concentrate force against one enemy at a time

Without hindsight or omniscient information, how should Sauron conduct the War of the Ring?

Guard Mount Doom, concentrate the main army against Gondor, then defeat the remaining enemies in sequence instead of attacking everywhere at once.

Without hindsight or an omniscient view, the proposed strategy begins by guarding Mount Doom and identifying the most immediate threat. In the novels, Sauron attacks Gondor, Lothlorien, Lake-town, and other enemies at the same time, dispersing an enormous force across several battles. The alternative masses the main army against Gondor, overwhelms Minas Tirith, and then moves against the remaining opponents in sequence. The Black Gate would hold the approach to Mordor while that campaign proceeded. Saruman would also receive a trusted lieutenant to help train his Uruk-hai and secure their loyalty to Sauron. The proposed improvement combines concentrated force with control over an ally's troops, rather than assuming those troops will remain available without supervision.