We know from the above table that you have to play the G major scale over this chord progression. This means that you can play any mode of the G major scale. You do not play modes of the G major scale, then C major, then A minor, then D major. If you played those scales, your music wouldn't sound right, because your music is not in those keys. Therefore, as discussed, for progressions in G major, you can play modes of the G major scale.

Now we know that we can only play modes of the G major scale when we are in the key of G. But which modes do we play, and when? Basically, you can play any mode over any chord. If you had a C chord, you could play any one of the seven modes over it. Which mode you choose depends on the sound you want. You can play C lydian over a C chord and get a different sound than you would by playing a E aeolian. Both modes are in the key of G, but they will sound different over a C chord because each mode will require you to use different slides, hammer-ons, pull-offs, and bends.