He may just know that piece of the river well enough to run it. Or he may have a GPS track through it that allows him to run it. If you're familiar enough with the area you can run it. stumps don't move.
Stumps don't move, but contact with the lone wolf you never know was there can be dramatic. The same goes for large "floaters" that become submerged as they waterlog and settle into a new spot that was once upon a time along the path of an angler's safe route through an area.
In that case you shouldn't ever run above idle anywhere. "floaters" can be anywhere on the lake, not just in the coves.
You need to work on reading comprehension. First, I never said that floaters were only in coves. I didn't even mention coves, in fact. Second, I was speaking about what you get AFTER a "floater" has waterlogged and settled to the bottom. (Check my post for that.) This is a bigger concern when the water is shallow enough that a new obstacle on the bottom is close enough to the surface to snag lower units. You said I need to idle everywhere if I apply my risk logic. That's not true either. While floaters are expected in the open lake, when they sink in DEEP water, they become a non-issue. Yes, you can hit a floater anytime anywhere there's water to float it. My discussion was related to the ones that have sunk. Think of this like planting new stump that wasn't there before.