What limit-up chasing taught me about order book depth

Some markets cap how far a stock may move in a day, and when a name pins against that cap the entire question becomes who is still willing to sell there. We have no such cap, but the same situation shows up whenever price runs into a level everyone is watching. And what you have to read is identical. What they watch is the size of the buy queue sitting at the limit price. A stock pinned at its ceiling with an enormous queue behind it is a different animal from one pinned there with a thin queue, even though the price is identical. The queue is a measure of how much demand couldn't get filled. Our version: at any price level that's holding, the question isn't "did it hold" but "how much size is behind it, and does that size refresh when it gets hit." I'd been reading levels as binary, held or broke — and completely ignoring the depth behind them. I now look at whether resting size at my level replenishes after each hit. It doesn't require limit-up mechanics. It just requires actually looking at the book instead of the chart.