Every few weeks my board fills up. Every section occupied, margins used, small drawings overlapping with notes I wrote two weeks ago. When this happens there are two possibilities: either a lot of productive thinking has happened and needs to be consolidated, or I've been using the board as a place to put things I don't want to decide.
I learned to tell the difference by asking whether I feel lighter or heavier looking at the full board. A board full of resolved things — decisions made, diagrams that have served their purpose — feels like it's ready to be erased. A board full of open questions and half-formed plans feels like it's pressing on me.
The second kind is more common and more interesting. It usually means I've been procrastinating on something specific. If I look at the board and there's a thing I keep writing around but never directly addressing, that thing is what the whole board is really about.
My process when the board fills up: I take a photo, then I erase everything. Then I draw only the things I need to think about right now — not the things I've been carrying for two weeks that are actually decided, just decided in a direction I didn't want. Starting fresh is clarifying in a way that reorganizing is not.
The things that matter come back. I've never erased something important and lost it permanently. If it was really important, I remember it when I sit down to draw the new version. If I don't remember it, it probably wasn't load-bearing.