How do Gains occur?

I'm curious about this. I've only been back to Pe'ing 10 days ago, so I dont necessarily expect any gains yet, but I'm wondering how they work. Does the penis expand in a way such as a growth spurt over night, or does it slowly get larger each day ? B/c i've never measured myself each day to determine this.

I believe every session, like where guys tell of being 0.5" longer or 0.5" thicker or something, kind of resets the penis to get used to that size. Eventually the tissues get used to being in that state and if you keep giong you progress into the next 0.5" and the process continues. So I guess it gets bigger every day, although it may not be measureable on a ruler for a little while. I can't see it going through a growth spurt unless something gets detached internally....