Having just read his book on Rossbach and Leuthen, I can rustle up a few stats.
At Leuthen, Zieten has 53-55 squadrons on the right wing. Dreisen on the left has another 50 squadrons, and Wurttemberg yet another 30 squadrons farther left. Oddly, this doesn't quite square with Duffy's summary of the Prussian army, which indicated 120 squadrons, for a total of 9,800 cavalrymen. Nevertheless, the cavalry on the two wings was clearly in substantial numbers, the regiments and squadrons of which largely acted together. Also interesting to me, is that the proportion of cavalry to infantry is 1 : 4 -- an impressive ratio.
Duffy's information on the Austrians at Leuthen is a little more vague. Nadasdy's corps on the left starts off with cavalry divided into two bodies, one of 5 regiments (3 Saxon, two Husars) and the other of 4 (all dragoon regiments). Serbelloni's left wing of cavalry boasts some nine regiments (7 cuirassier and 2 dragoon), while Lucchesi, on the right, had another nine regiments (6 cuirassier and 3 dragoon). Lucchesi's wing, reinforced, attempted to initiate a significant massed action during the battle, and was reinforced up to 65 squadrons, but is bushwhacked in teh flank and rear by Dreisen, whose command had been unseen behind a low ridge.
At Rossbach, Prussian cavalry (5,400): infantry proportions are 1 : 3; even more impressive than at Leuthen. Seydlitz takes command of 38 (in 8 regiments: 5 cuirassier, 2 dragoon and 1 hussar) of the army's 45 squadrons to execute the turning movement that charges the head of the the Franco-German during its march. Surely Seydlitz's attack would constitute a massed cavalry charge :o)
So you can see why I look askance at an assertion that implies that massed cavalry charges were something of which Prussians and Austrians were incapable, or that hints that it is not until the Revolutionary and Napoleonic period that they materialize. :o)
Cheers - Howie