Yes the window to redose while on Mescaline is 2-3 hours and the earlier the better. Personally id dose the LSD an hour after i took the first part of San Pedro. The Cactus is good to take split up in three parts IME.
Havent combined Mescaline and LSD yet but i plan on doing it sometime soon. Just gotta pick up some more L sometime soon. Have combined San Pedro and Mushrooms a few times and it's the type of trip that will show you the beauty in every blade of grass, Tree and Clouds floating through the sky. The connection i feel to nature is incredible.
Feel like it would be just as beautiful with Acid