Sure, I can explain it, but I think you already did it for me. Easy fish to catch are those that typically always inhabit the same spots. For example, go up to LOTW and fish with a jig and minnow any time of year, on just about any pile of rocks deeper than 10 feet and you will most certainly catch a walleye, right? In fact if you find a pile of rocks with suitable forage, you may catch 50 walleyes.
Now muskies on the other hand, as you stated, start in one place early in the season, then move as water temps and forage dictate. Only to come back to the same spots they started at some time, again as water temps and forage dictate to spend their fall.
I didn’t say muskies were impossible to catch any time other than the fall, simply that it is difficult. So much so I know of guys, as well as guides that have gone days, if not weeks without actually boating a fish.
I believe the context of this conversation from the beginning was how a guy that isn’t up there every day, can find and fish muskies on the US side of the Rainy.
Fall, in any lake that has a Whitefish and\or Cisco population, most certainly offers the best chance of catching a muskie on shield lakes simply because the majority of a favorite food source is concentrated on very specific types of locations\structure. Essentially taking the much of the guess work out of musky fishing.
Happy to hear your guiding acquaintances are so good on LOTW, perhaps you would like to share their names and contact info should I ever want to venture up that way and catch a guaranteed fish.