Its the same as when some one hires a "white hunter" when going to a totally new and different location to hunt "big game". When in totally unfamiliar territory, with a somewhat limited time allowed, a person wants the trip to be as pleasurable as it can be.
We dont use any "guide" when fishing local waters...mainly because I at least ( not my wife) grew up here and have spent more than 50 years wandering up and down the banks of the local streams...but water such as the Snake river ( this next trip) is as unfamiliar to me at least as maybe my property here at home might be to you.
Of course I can ask locally...and I do..but having either first hand knowledge or having someone with you that has first hand knowledge of the waters is EXTREMELY helpful.
If you came to my area lets say pheasant hunting, again with a limited amount of time, would you know the area(s) to hunt in? And yes, even out in the fields especially with your trusty bird dog at hand is pleasurable, maybe...just maybe the same situation AND bagging your limit might make it even moreso...??
And, now that I'm retired I get the richest rewards of all by being able to spend my summer days on Montana's rivers chasing trout, and I don't waste any time in getting them. I'm one rich guy!
It appears that you spend sufficient time to learn the waters "out west" that at this point I cannot spend. My wife still works and has a finite amount of time she is allowed vacation...so while she works I stay home. She is "close" to retirement and when she does THEN we will spend a lot more time in the west from southern AZ all the war to MT....one reason why we purchased the motorhome we have. Its a "rolling condo" for us and allows us travel and freedoms that otherwise we couldnt have.