Lots of initial timing scoop?

[PJS50]

I am glad to see you guys talking about this because I have a lot of questions about this topic also..
I have been looking into a new carb for my 460 crate engine and have been looking at the mightly Demon carbs...
1st, how the hell does the carb "know" what the initial timing is set at and why does it make a difference unless the carb is running rich on the idle circuit? Looking into that 4 seconds flat website, I kinda understand the advanced initial timing/idle concept but it seems to me that the advanced timing issue is just dealing with an "overly rich" mixture in the first place. Couldn't you get the same results by leaning out the idle mixture and backing off on the timing a bit? I think that I am missing something.....
2nd, when I picked up my Cobra, the initial timing was set at about 13 degrees and I was getting hesitation in off-idle performance and a bit of run-on when I shut it down. I don't know what my MSD distrib.is set for advance but when I backed off the initial timing to 11 degrees, I gained a little bit better throttle response, lost the run on, and also noticed a little bit extra tire spin on a good 1st to 2nd gear shift :-). I am running an admittedly poor Holley on the car now (vac. secondaries, electric choke, single pumper; what can I say the previous owner was NOT the wrench type!). I want to loose the air horn and get better flow to the engine but the Holley/Demon/initial timing/cam duration/tire diameter/leap-year-or-not issues are confusing me...
It didn't seem this confusing 15 years ago with my '67 Mustang which I could get to run like a raped ape with my eyes closed...
What am I missing?