A-yup. I hate "it depends" as an answer", but it's a real thing, unless all the criteria are known...and you're familiar with the lake.
Funny you should mention that...
I spent the 4th of July week on Clearwater/Pipestone some years back...and conditions hit me hard. Temps were 80°+, I'm not sure I saw 10 clouds the whole week, little to no wind...and if all that wasn't enough...I wound up right in the middle of God's own mayfly hatch...to put it in perspective for folks who are not familiar with the phenomena, there are rafts of dead mayflies in the back of bays that are so thick they look like a layer of foam, or pale algae.
Few people were catching much of anything, and when they did, they were bloated with mayflies and mayfly emergers.
I saw a 30+ inch pike swimming along the surface with it's mouth open skimming mayflies off the surface, which was cool...but geez...the fishing just blew...
I had fly rods with me, as I intended to chase smallies with them, but I'd intended to throw poppers, divers and streamers (leaches and crayfish are normally killer up there).
About three days in...I'm rummaging through my fly gear looking for something (probably a bottle of Hemlock so I could end it all)...and I find one of my fly boxes that I use back home for trout.
It's got 10 or 15 mayfy patterns in it...
Oh, baby...
I ran up-lake to a shallow bay I'd seen a buncha smallies in a couple days earlier...tied on the biggest mayfly I had on a 6 wt., flicked it out there...
I don't think I went five casts all day without catching a smallie. It worked pretty much everywhere.
I caught a half dozen walleyes...on the surface...too.
I fished each fly until it was so bedraggled and beat that even extreme applications of flotant couldn't keep it up on top.
People cruising by kept stopping to ask me what I was using, my standard reply was, "You don't have any." then I'd show them.
The mayfly flies lasted about two days....then I said, "Screw it." and drove home.
Still makes me smile...