I've always understood it that Crappie start bedding on Northern shores (where proper conditions are available) because the Sun warms those waters first & the S/SW winds blow the warmer surface waters towards those banks. But, they are also subject to moving into sheltered pockets on any bank, even if they're very shallow ... as those shallow water pockets warm quickly.
They can't & won't bed where wave action is too turbulent or creates too much current/water movement, because they can't keep the eggs/fry under their control in those situations. They can & will bed deeper than normal ... as long as the water temps are in their preferred range at that depth & the water clarity allows enough Sun penetration to that depth.
... cp