I did not test it scientifically but I had the same feelings. The more men per unit are lost the greater the loss of unit experience. It seems to have nothing to do with the ratio of loss to unit strength. That can be accepted because if you replenish a small unit more experienced men were left in per cent of newbies to form a structur for the unit.

Experience was a great factor in the 18th c., a greater factor than in the national wars to come later, where you could recruit from a very large pool of young men, train them shortly and waste them on the field. 18th c. soldiers were very precious and most generals tried to conserve the manpower of their armies. It was a big difference wether a unit would break when the enemy line came near 100 paces (more experienced troops perhaps would broke only at 30 paces or not at all) or even ran away at the first fire. Also the performance in battle field marching and loading procedures under field conditions differed a lot after some experience.

I think I have too many soldiers and too many armies. I'm in 1774 in my Prussian campaign and never got a unit with 4 chevrons yet. My best units are 4 cavalry squadrons, 3 line infantry and 2 Sepoy battalions with 3 chevrons. It's a pity. I will shorten holiday for the units.