I wonder if it would be more interesting to have resting go faster, but have the men take significantly longer to stand up when they're laying down. The math there would be less realistic perhaps, but it might lead to more realistic and fun behavior -- if you let your men fall out to rest near the front line the enemy might take them off guard, aka shoot them while they are slowly getting up.
Honestly, they do actually take a bit of time to get standing as is, especially if you purposefully issue the order yourself. If you let the AI handle it, the unit is usually up as a single man, basically. It's actually somewhat annoying to have to sit and wait for every last man to stand up and get in line while under fire, but perhaps that was intentional to simulate the effect you're talking about. Plus, as soldier mentioned, with the LoS changes, being caught off guard is entirely possible. I think Kester now uses the assault column more than any other formation, even line. It used to be fairly thrilling to watch an attack go in like that, one of the first I saw was at the angle, so it was a pretty desperate affair but definitely cool to watch. Now, it's fairly well old hat.
A clarifying statement about "reserves."
It's INCREDIBLY subjective
In the attack, however .... reserves don't really apply.
Quite. Wasn't meaning to attack your position (no pun intended) as originally written, just to try and make this more of a discussion as per B2S. It really is a lot about personal preference. Rotating regiments in and out of the line is somewhat complex so kudos to those who can do it well.
As for the attack tactic described, as I understand it, this was what Napoleon used to a great extent, except his attack columns were more precisely that, meant, I think, to have a narrow front to punch through the enemy line and then exploit the break. It wasn't entirely novel, sure, and you have proof there, although that's over a year after the present battle and works better, probably, against more static positions.
I have come across discussions before, however, of units and men refusing to obey orders they regarded as suicidal, to the point that most of the veterans of the AoP were actively refusing to expose themselves in a manner they regarded as needless by the Overland Campaign. This, in turn, has sparked a debate about whether these men were cowards or what their particular motives might have been. I don't have any of the sources readily available anymore, even my computer they were on is out of commission right now. So I reject your reality and substitute my own. Resistance is futile!