P-mode today is virtually always "shiftable programmed automatic" mode, as it was called when first invented.
P mode can usually deliver fantastic results in modern Nikon cameras, whoich have 3-D, Color-Aware, multi-segment lght metering, as well as D-istance aware (AF-D, AF-S, AF-S G, and AF-S E series lenses are ALL D-aware) flash metering and exposure regulation/balancing, as well as focal-length-sensing. P-mode in Nikons works in ambient light conditions, AND with flash enabled.
P-mode can be SUPER-fast when you wish to be able to go from a very wide-aperture, shallow DOF shot, then immediately change to a mid- depth of field shot, or perhaps to a deep depth of field shot, in literally, 1 to 3 seconds, with the same level of exposure. Shutter and f/stop, both linked to one fast-to-operate control wheel. BAM! BAM! BAM! Three exposures, just about as fast as the wheel can be clicked.
With an f/1.4 lens, you can fire off shots at f/1.4, f/1.8, f/2, f/2.8, f/5.6, and f/11, meaning at SIX, different exposures, as fast as you can click the thumb-wheel, and in lock-step move the aperture and the shutter speed. Consider that each full EV value has three clicks of the wheel....if you have a DUAL-wheel camera, you would need to adjust the f/stop on one wheel, and the shutter on the back wheel...do you want to adjust EIGHTEEN clicks on the front wheel and also a matching EIGHTEEN clicks on the rear control wheel, as in the above scenario? I did not think so!
For the lower-end cameras, the ones that have the so-called "one-button layout", P mode is more valuable than it is on the more-expensive cameras. P-mode inter-connects f/stop and shutter speed directly,and shifts of the program can easily be made via the main command wheel. Users of Nikon D3xxx and D5xxx series actually BENEFIT from having a fast, easy P-mode option.
If you have the camera in an appropriate light metering mode (12mm circle center-weighted for exampler, or in Matrix mode, for example), with the right exposure comp for ooddball backdrops, you can easily easily NAIL perfect exposures, from the lens wide-open and the shutter at 1/4000 second, right down to the mid-f/stops, or to the small f/stops, in seconds. This is why "shiftable programmed automatic" was considered such a huge,huge deal when it was invented.