theory and fact sometimes agree -and -sometimes not . a really short span wing may simply --settle evenly - as spanwise flow increases
a longer wing may start " dancing" -as each panel stalls-call it tip stall -whatever .

As long as we understand that flaps simply reconfigure the airfoil- and angle of attack of the wing is NOT the same problem on all planforms , then the stall and it's effect can be better understood.
as an example : add inboard flaps to the demispan of a Cassut box wing aircraft ( aspect ratio of 3.3 to 1)
do the same thing to a -(you pick it) a 7-1 aspect ratio lightcraft - both with same wing loading and area .
The extremely low aspect ratio setup will act differently-and remain more stable
N/Y?