What would Longstreet have considered getting a "lodgement?" After all, portions of Armistead and Garnett's brigades breached the Union line at the Angle. But on the other hand, if Longstreet had waited that long to send in McLaws, it might have already been too late.
McLaws claims he was not even informed of the plan. I cannot encourage you enough to read what McLaws had to say about it. Here's an excerpt.
"It was not notified that it was in contemplation even to make any further attack by either Hood's or my division, nor was I informed that it was the intention to assault the enemy's centre with Pickett's division, with the assistance of troops from other corps. I was not told to be ready to assist, should the assault be successful, nor instructed what to do should the assault fail and the enemy advance. I contented myself with reconnoitering my ground and vicinity in all the directions necessary for movement in any emergency, and took my position among my troops.
I became early aware that artillery was concentrating along my rear, on the crest occupied by my line, before I advanced, and that not only the corps artillery but the guns from Hill's corps and others were preparing for a grand opening. And when the numerous guns opened, shaking the very earth between the opposing armies, the shot and shell from the batteries on our right poured over my command; those of the enemy crossing ours, going in the opposite direction, but all bent on the same mission of destruction.
Not a shot, as I can remember, fell among my men. We were resting entirely undisturbed, excepting now and then a bomb shot would come from Round Top, fired at some of us moving about, and got in view of the batteries, in mere wantonness, as the chance was very small and they did not care to waste a shell on one, two or three."
Read the whole essay
https://civilwartalk.com/threads/vi...fayette-mclaws-on-july-3.159910/#post-2090020