Janet wrote:
More likely overcrowding. IME, such rampageous growth that the flowers
get lost in the foliage and tangle, beans get bent instead of hanging
loose, and you don't notice them until they are huge and tough.

I've found the best way to avoid that is to grow purple, yellow or pink beans.
:-) A lot harder (although not impossible) to lose.
Having said that, I quite enjoy the hide and seek aspect. Not as much as I do
with the red and white currants, which still give me a thrill when I lift a
leaf and find a little treasure trove ... ahh.
(Got a similar but not-quite-as-good thrill when I noticed the raspberries have
suddenly come out early today! Huge ones, too - did some seriously heavy
weeding this spring, which hasn't got rid of all of the weeds despite my best
efforts, but it seems to have seriously improved the crop, which were all small
and a bit squishy last year)

If you want a heavy set of nice straight beans you can see to pick at
the optimum size, then one plant per cane is plenty.

Nick has experimented with his bean frame this year, s othat the beans
should hang down on the outside instead of on the inside, in the hope that
it will help with shape and picking. It was a nice idea, but since none of
the damned beans will grow cos of the slugging ...