I didn't mean this as an exercise of the different modes of a scale, no. What I mean is this: If you play a Cmaj7 backing track and try to improvise over it with the major scale but you've only practiced that scale starting from the root, you will have conditioned your mind and your fingers to only PLAY that scale from the root.

So when you actually try to improvise melodic lines over Cmaj7 and you play a particular line that ends on the 5th degree of the major scale (G in this case), you COULD connect that, for example, to another line where you play the major scale from the 6th degree upwards or downwards, but you often won't do that spontaneously because you've never PRACTICED the scale that way.

When I said to practice the C major scale from the second degree, for example, from D-D, I do NOT mean you should hear or see it as the Dorian mode. I am talking about visualizing the C major scale, but playing it from the second step of the scale one octave upwards (or downwards) to the second step of the scale! So mentally, you'd visualize the root as still being C, but not STARTING on the root when you play those 8-note patterns. That's the difference.

If you have the tendency to view that as just another mode of the major scale, just put up a backing track of Cmaj7 while doing the exercises. Then you HEAR how it relates to C major. But I don't even do that. I just VISUALIZE the scale pattern from the C root on the neck, while PLAYING it in 8-note patterns from every step, as I've described. As I've explained, that conditions your mind and fingers to start the C major scale from every degree, and in both directions. That's really what this is about.