The Guitar Major Scale is the first scale most music teachers would want you to learn and get under your fingers, into your brain and out of that huge amp that is sitting there in your room slobbering on itself waiting for you to show it some love.
Why? Because most of the rest of the modes and scales are derived from the major scale.
Getting this down so good you can do it while you are asleep will take some practice time.
With a metronome or with some other form of a machine, such as a drum machine.
A scale is just a boring scale until you give it some rhythm. It activates the brain and pretty soon, that scale is sounding like music.
Speed up your playing a little at a time until you can play it blindingly fast. Why?
Well if you can play it that fast it should be so natural that you don't have to think.
When your playing becomes so natural it flows out of you you enter a state of flow. This is when time slips away and before you know it hours have past. Not just for the guitar major scale but for anytime you pick up that guitar. Go for that flow state. That is the secret of greatness.