From your comment, I draw the conclusion that you've now come to the insight that there's more to M mode than just mimicing what the camera could do for you, just quicker and better.
For others, let me just state it again: If you use M mode to set an exposure that sets the metering needle in the center of the scale, for each and every photo you take, then there's an exposure mode which does that better than you do. Whether it's P, Tv or Av depends upon if you change the exposure time, the aperture or both to match your needle to the center marker.
The purpose with M mode, and the circumstance where it actually offers you photography with less manual intervention in manual mode than in any automatic mode (sounds like a paradox, but it's true) is when the reflectivity of the subjects change, but the lighting is the same. Meter, experiment - do whatever you like, until you have got the exposure you like. Then you can keep on shooting, regardless of massive concentrations of white shirts, black trousers, herons or ghosts (the non-glowing type) within your image frame. As long as the light is the same, the exposure will be the one you want. Manual mode is automatically handling different brightness in the subjects. An automatic mode will require manual intervention for each shot, where the circumstances change.
But where the light itself is changing, there the automatic modes have their field days.
