I think it depends on how the camera decides on which pair of settings (for aperture and shutter) it chooses when you're using P mode. Over the many years this has been available, as the light levels have varied some cameras have simply changed both values a step at a time. Others have taken lens focal length into account, and others frequently allow the offered settings to be adjusted whilst holding the exposure constant. I found the P mode on my Minolta X700 quite exasperating due to limitations at the time of what it displayed in the viewfinder, and instead I normally relied on Aperture priority mode.

Nowadays with my Canon 5D and other EOS bodies, I'm fairly happy to stay in P mode much of the time, selecting Av, Tv or M mode as required by what I'm shooting. P mode seems sensitive to the focal length of the lens in use, so camera/lens shake isn't much of a problem. However, shooting birds, I do adjust the exposure compensation quite a bit so as to keep detail in the white feathers of swans or little egrets. It's amazing just how much compensation is necessary to stop them burning out. (Like minus 1-2 stops, and I do check with Spot metering sometimes but that then needs compensation of +1 stop or more... Thank goodness for digital and I can learn on the job!)

HTH