I have actually found reversing the logic works well for me.
I usually shoot in P mode, the camera has a higher IQ than I do so I let it do the work for me
I use A/ AV aperture mode if I am shooting fast moving subject and need a high ( or slow ) shutter speed. by choosing A you can select the most appropriate aperture ( f2.8 for high speed ) and the camera will automatically choose the highest shutter speed available for the exposure in changing light conditions.
Similar for S/ TV shutter priority time value if I need a long DOF
By choosing the slowest shutter speed that is usable at the time I know the camera will choose the smallest aperture available.
Using flash depends on the job and the subject I can use any mode depending on the situation.
As with anything these can be changed to suit the job or the situation but try the system, if you can get your head around it, it works quite well.
"Photography to the amateur is recreation, to the professional it is work, and hard work too, no matter how pleasurable it may be."
( Total NIKON bigot )