Ask a founder how confident they are in their understanding of their customer and you get adjectives. Force a number (zero, twenty, forty, sixty, eighty, a hundred percent) and something changes in the room.
Writing 'guessing: 0%' next to your own ecosystem map is uncomfortable, and that discomfort is the product. A written number is falsifiable. It invites the question no adjective ever does: what evidence would move it?
The number is not the point; the honesty cascade is. Once one assumption is marked 'guessing', the conviction propping up the others starts to look like what it is. That is when validation stops being a ritual and starts being a search.