When I made my last post, there was a bit of a discrepancy over what exactly your poker box is. The reality of the situation is that it doesn't matter what specifically we define the box as, but rather that we understand it's purpose.
In fairness, my own personal view of the poker box was in line with Reid's. The box is this big mansion with lots of secret doors. Various experiences give you the keys to new doors, or provide you with the knowledge that they exist. Everyone's box/mansion is the same size, but some people realize that there house contains more than others'.
The other view might be that our box can expand, but we still cannot think outside the box because once we do that, our box has just expanded

. It's fairly abstract but I think the general point was appreciated, which is what I wanted obviously.
I considered listing all the ways in which I thought our poker box might expand or shrink, but, since many of those are intuitive, I'll touch on a couple points that may be useful:
-Our poker box temporarily GROWS (technically returns to full capacity) when we take a short period of time off. This is the case because playing temporarily taxes our minds, which SHRINKS our poker box (1).
-After a certain period of time off from poker, our box temporarily SHRINKS (we become 'rusty') (2).
-Overplaying does not allow our box to fully recover from the last session, which makes it temporarily SHRINK. If you are in a perpetual state of overplaying, consider the effects on your poker box.
(1) Playing actually allows us to experience situations that have the ability to expand our poker box permanently, but most of the time we do not take advantage of it. Whenever we encounter an interesting spot, it usually receives a "hmm, interesting" acknowledgement, and, if it is particularly interesting, gets brought up to friends or posted in a forum. However, we almost never actually conquer the spot; we do not take enough time, playing with ranges, opponent types, various streets before/after, to be fully confident the next time we enter a similar situation. This uncertainty prevents progression, and causes us to become results-oriented. We learn to simply change what we will do next time based on what happened the last couple of times.
(2) Going from personal experience, people usually underestimate the amount of time in which it takes us to shed the rust. When taking a significant time off playing or focusing astutely on a game (NLHE, PLO, whatever), I would attest that it takes 3-5 full days to return to normal. This includes playing with moderate-heavy volume, and reviewing/re-familiarizing yourself with the situations of the game.
One of my central themes seems to be: Play less, review more. In the future, I'll go over what that means -- for now, consider the following:
How many really good HS grinders that you know force themselves to play? The answer is very close to zero; almost every one plays when they want to because they want to. It allows them to both mentally recover from a previous session, and to continue playing their A game. A very high volume 2/4 NLHE grinder recently figured that playing too many hours cost him about $150,000 over his career. He made about $100,000 from rakeback, and lost about $250,000 from being in games when he should not have been playing.
I have a lot of things that jump through my mind that I can talk about, but I want this whole experience to be more feedback oriented. Ramblings tend to be all over the place, so don't be afraid to ask for clarification if needed. Also, I would appreciate if you told me what you thought of this post, and what direction you want this series to go in. As an exercise, post a couple ways that your poker box can shrink or grow that haven't been mentioned yet (by me or my user comments before your's)
Greg
PS. I am going to be creating another monumental 6m 5/10 NLHE multipart sereis soon. PokerStars or Full Tilt?