Am I the only one who thinks that leaves 'praying' is simply the plant adjusting the angle of its leaves to increase reception to light, therefore absorption? Almost anything a plant does that's automatic is for its benefit and is the result of many generations of evolution.
I think it's adjusting for sure, but not necessarily for light reception in all cases.
Example. Outdoors, the plant is stationary. The earth rotates, changing angles of light that hits the plant. In my garden specifically, the sun will never touch the backside of the plant, yet the petioles will be firm and the leaves at attention... In the shade.
They aren't adjusting for light reception, but transpiration since the front is taking in all the energy, yet the whole plant breathes.