This is a cross post with shit just works, check both instances out!
I hate to be “that guy” but I am fairly sure that Schürzen (German side skirts) were added to tanks to deflect AT rifle rounds that were being encountered in large numbers against the Soviets, not a measure against HEAT.
The Sherman sandbag protection has also long been a point of controversy. I believe the wartime tests showed that sandbags were somewhere between useless and of very limited use. I think this is accurate given that the spacing provided by a sandbag against HEAT would not provide much difference, and that modern external (external add ons being different than some internal designs) spaced armor is largely misunderstood by the layman in that it doesn’t usually rely on prematurely detonating but in catching the round and dismantling it or deflecting it.
I do apologize for being light on sources, as I am on the go at the moment which makes research tough and I don’t have physical resources at hand. I will look to try and come back and fill some in.