Hitler having person control of 2 key panzer divisions cost them the battle for normandy and in turn the war.
As much as Rommel deserves his respect, I find it silly people put way too much emphasis on the different ideas about how to place the divisions and their respective deployment. Given how long any kind of armoured division can stretch in total length (hint = it's three digit number) during any kind of battlefield march even in good road conditions, France is relatively concentrated in that regard, and as many other generals noted, once they are deployed or have to move anywhere as reserve or not, they are chiefly on the mercy of good luck and how fast they can get there before the lines get clogged by air power. Not as much attrition or any kind of damage really, but simply preventing any focused and concentrated movement and clogging resupply chances pretty well altogether. Major troop movement already was restricted to night time only or limited in size because hey, even if 98% of the ordnance would miss or only damage soft skinned vehicles, you are not exactly going anywhere when you have few flights of aircraft bombing and harassing the fuck out of you. All it takes is few clogs on the road and the entire column is halted until it can be cleared. Sure, it would have given them a lot better chance to defend against the initial wave and perhaps even succeed, but had something gone wrong, it would have been
instant disastrous loss of Panzer reserve since any organised retreat would have been very difficult to pull off, and most of the equipment would have been left behind, which would have probably resulted in very rapid collapse of the front, even if they might have given very bloody nose to the Western powers.
Prime example between jumping in pool of piss or taking bucket of shit down your neck. Your choice.
Oh, and arguably the closer they are at the beaches, the greater risk of adding naval artillery as another factor to restrict movement once the location is pinpointed. Once again, it's not as much about attrition as it is simply about complete denial with some attrition involved, especially when most of AFVs don't have the privilege of staying in coastal fortifications that intentionally halted their activities for a moment in order to avoid drawing fire.
