The US effort had two fronts, MacArthur's which relied on island hopping and up through New Guinea, which was a bit unimaginative really, and what Nimitz was doing in the central pacific, which was directed at Guam/Tinian/Saipan as bases for the B-29s. The Phillipines could have been bypassed. Peleliu should have been bypassed, it was irrelevant, and a very nasty fight that took 1st MarDiv out of the Iwo fight. We wanted Iwo Jima as a landing field for damaged B29s.
Of course, hindsight and all that, the Japanese should have been more careful at Midway and should have launched a third attack at Pearl.