A part of it is inside your message
Thank you for your correction, I modified n.n
I was actually talking more generally with regard to discipline.
We certainly know that both sides were actually really quite bad at following the manual of drill even at Gettysburg (which was where the quality of the armies was said to have peaked) because of all the thousands of rifles that were found abandoned on the field with more than one cartridge loaded into them, indicating that their users either forgot a step of the loading process (I'd guess the percussion cap) or
forgot to fire.
The culprit here is that they didn't have enough practice, and in November 1864 Warren said:
'The command... consisted, first, of the First Division... 4,707 strong, of which 1,247 were ignorant of the manual, and 2,803 had never fired off a musket. Second, of the Second Division... 4,704 strong, of which 104 were ignorant of the manual, and 812 had never fired off a musket. Third, of two brigades of the Third Division... of which 298 were ignorant of the manual and 298 had never fired off a musket.'
Consider that. November 1864 is after
all of the major battles in the East, and Warren is reporting that his command (5th Corps) has nearly 4,000 men who have
never fired a round.
This is also attested to elsewhere:
'Circular, Headquarters, Army of the Potomac, April 19 1864
To familiarize the men in the use of their arms an additional expenditure of 10 rounds of small-arm ammunition per man is hereby authorized... Every man should be made to load and fire his musket under the personal supervision of a company officer. It is believed there are men in this army who have been in numerous actions without ever firing their guns, and it is known that muskets taken on the battle-fields have been found filled nearly to the muzzle with cartridges...
By order of Major-General Meade
Chas. E. Pease,
Captain and Assistant Adjutant-General'
But the armies in general could stand fire but not really manoeuvre under it, and they were bad at keeping their formation in the advance or under fire (at least by European standards). There's a reason why armies drill a lot.
They also had a real tendency to slow down, go to ground and fire back rather than pressing attacks - the typical attack is an attack by fire rather than a shock action, and when shock actually took place it did break into the position regardless of whether or not it had works.
The examples of shock action working in European armies are many, but I'd say the Battle of Solferino is a good example - the French charged at a run and actually took less casualties than the defenders, because their discipline worked.