Lee was an engineer. His training and personality leant themselves towards a methodical and unfortunately conventional style of warfare. The Confederacy could not win a conventional war, nor one which featured a tactical offense such are Pickett’s Charge.
He was also burdened with Jefferson Davis’s insistence on a basically linear defense.
More flexible attitudes and more irregular forms of Partisan and guerilla warfare, and a healthy measure of bloodlust would have served better, IMO.
Lee tried to fight a limited war against an opponent who fought a total war. Sherman, not Grant, won the war for the Union, and he did not do it through conventional means.
Nevertheless, he was a very gifted commander, careful of his troops’ lives and welfare, and tried to limit the horrors of war. A noble man, but too measured and restrained to prevail in a total war.
We would most likely still be living with the negative consequence of such a war today.