A lot of other people said it. If you try and be too formulaic, your playing will dwindle. I really don't believe in rules for chord progressions, because there are so many chords. If everyone used the same rules, everyone would sound the same, and well, a lot of guitarists do sound the same. I usually find the root notes that I want to use, and then add a note at a time, without thinking about what chord I'm constructing. There are still a lot of chords out there that have yet to be classified.
You can sneak in a few notes of any mode with any style of music. Harmonic Minor works really well with blues scales, but if you're playing straight blues then you won't want to use too many notes from harmonic minor. Just a few. Or a touch of some jazz works nice. Kind of like Hot Tuna or Charlie Batey.
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