[kahoon]

> There's clearly a selective advantage for some of those 'configurations', but how many generations would it take for each genetic mutation required to make a lichen katydid or an orchid mantis to converge?

If you pose the question like that with the posteriori knowledge in mind, then yes, these configurations are highly improbable. I think another question that could be asked is: How many generations would it take for some mutations to produce some camouflage effect in some of the millions of existing species? Surely some mutations​ that produce camouflage effects will happen.

[mikekchar]

Some changes can happen really quickly too. If you look at breeders of fancy pigeons or fish, they can do incredible things in a relatively small number of generations. Of course, breeders are generally much more selective than nature, but it gives you a lower bound on what is possible.