Wow, good question, with a lot of interesting responses.
As a relative newcomer, I'm still experimenting, in part just to prove that there's no set way and I can change on a whim or adapt to varying circumstances.
I like the freedom to sometimes do it one way and sometimes another. I like discovering what else changes when I fill the bowl more densely, or when I only smoke half a bowl, or when bits of flake stick out the top.
My most recent delight was discovering that I could dump the entire bowl and start again with the same tobacco if it's not packed well the first time.
I'm now curious how y'all know how much to pack in a particular pipe. I mean, do you get to the point where you can grab a pinch that fits perfectly for the size of chamber you're using that day; or do you stuff it until it feels right and then gather the remainder back in the tin?