The Aleutians operation is ambigious. Its supposed to have been a diversion, designed to draw the USN out prematurely, then have them at sea & possiblly split between that group and a group remaining in Oahu. However there are claims the timing is off and reasons advanced for other Japanese motivations for that op. The core problem with it is it splits a portion off from the main fleet advancing on Midway. Yamamoto clearly wanted a DECISIVE BLOW, but then he authorizes a carrier & cruiser force, plus a amphib group and landing force to make a operation out of easy supporting range of his main fleet. Whatever the reasons it weakened the main fleet and complicated the overall operation.
Perhaps if the Midway op is run a month early Yamamto can postphone the Aleutians op a month or two.
Yeah but that is pretty much all of it. If he wants the DECISIVE BLOW, why the Aleutians? Why risk CARDIV 5 at Coral Sea? Why keep the big battleships 600 FREAKING MILES behind the carrier force? Why put the capable of fleet speeds light carrier Zuiho with the invasion force? Why have so many powerful and fast battleships/battlecruisers and heavy cruisers with the invasion force?
Let's face it, Yamamoto had a thing for complex operations with lots of moving parts.