Hey all,
I'm going to jot this down here because I can't sleep just yet and I didn't see too much written about the subject when I was searching earlier. Will probably come back and edit this in the morning when my head is clearer.
I'm a moderately experienced tripper (DMT a couple of times, 2CB a few times, and LSD ~15 times) and I decided I want to go back to back days tripping at a dance music festival. Based on the anecdotes I found on Reddit and around the internet, it sounded like 2CB day 1 and LSD day 2 was the way to go.
I took 30mg 2CB on day one and it was a blast. Felt like I was on MDMA but with some really strong visuals, just a great experience start to finish.
For day 2, I'd read that I could expect there to be somewhat reduced visuals but that I would still get the typical LSD headspace.
That turned out to be completely wrong. I only had a single voidrealm (pretty consistently 105ug tab) and I still got FULL BLOWN open eyed visuals. I put some diffraction glasses on and when I took them off my vision was still fragmented. For an hour. Absolutely fucking wild. Headspace was intense too. It was overall one of the most powerful acid trips I've ever had, though that could possibly be attributed to the environment. Either way, based on this experience, there is zero next day cross tolerance going from 2CB to LSD.
I hope this helps whoever comes searching for this information next.