What you're saying is not my experience
with boards and crossings. My feet know
you can put a board on a bank and a board on a board. Perhaps I don't know what you're saying.
If you're saying there are boards and banks that would not support this and that the person walking runs a risk until experience proves that crossing works, then I will agree with you.
But if you have a 2x12 or 2x24 board, it can support enough weight.