There is only one scale, the chromatic scale. All other "scales" are modes of this scale with some pitches more important than others.
Any "major scale" is actually 12 notes(actually more). The first 7 notes of the scale are the most important(the tonic triad notes are even more important).
The key of C has the notes
C C# D D# E F F# G G# A A# B
If we arrange them in a matter of importance, more or less, then
(C G E) (D A F B) (A# G# C# D# F#)
The patterns on the guitar(All the skipping and stuff) is simply avoiding the avoid notes.
There are many ways to play the 7 main notes and you can extend them several octaves up the neck.
Scales are just patterns used to develop technique and some logical concept of melodies. Melodies and music are not scales.
When someone creates a cool melody from creativity they are not using a scale to do so but may use the scale to avoid hitting those "bad notes".
Ultimately you don't have to and don't want to rely on scales but want to just have the melodies flow out. In this case you will be using the chromatic scale simply because the guitar is a fretted instrument. Usually to get close to this goal you end up having to practice scales for both a technical aspect and to reduce complexity(after all, it's easier to visualize 7 note patterns than 12).
Note that a scale doesn't have to start and end on the tonic/root. Jazz players tend to end them on the 9th. It usually helps to tend them on the tonic since it solidifies the mode. If you resolve on a clunker it will sound bad, mainly because you are emphasizing something that clashes with the tonic area.
Scales help being able to play a pattern and sound halfway like you know what your doing if you play in the right key.
Before you learn your 7 note scales work on your 3 note scales(arpeggios) and 5 note scales(pentatonic). The reason is these scales are more important in practice than 7 note scales because they encode chord information better... and most of the time you'll be playing over chords. (a chord is just a pattern with all the notes played at the same time or arpeggiated)
e.g.,
If you are playing over a C chord then the first 3 notes you need to be able to call up instantaneously are C E G(The chord tones). After that you need to be able to call up any add tones(D A F B) which you can get from your pentatonic. e.g., C major pent over a C chord gives you the D and A tones(also known as a Cmaj6/9 chord) while G major pent over a G chord gives you your B D A extensions... but guess what? C major pent and G major pent are the same patterns!!!
So essentially by learning just one major arpeggio shape you can get all kinds of music from country to jazz. It would be very rudimentary at first but if you really worked on it, it would take you further than your avg guitarist.
e.g., Over a C major chord, The G major arpeggio gives you the G B D notes which allows you to get a major9 type of sound. Ab major arpeggio gives you the notes Ab C Eb, which gives you a sort of bluesy sound if you use it right. D major arpeggio gives the notes D F# A which gives you a Cmaj13 type of sound...
But realize, all these arpeggios (shapes) are the same. Just the basic triadic arpeggio (shape). There are just a few of these major triad arpeggio shapes on the guitar. The biggest drawback to the guitar is that the B string makes us learn 3 times as many shapes but it also is what allows us to play 3 times as many chords.
But if you play likes this, unless you happen to be very advanced at it, you'll sound quite a bit polytonal and as if you are playing in the wrong key in some instances. To be able to make it work you have to add more notes.
The C major arpeggio + the G major arpeggio = C E G + G B D which gives you your Cmaj9 sound... same as a above. But this time you can learn this as a pentatonic = C E G B D scale!!! By learning this pattern you'll consolidate your visualizing into larger chunks on the fretboard... But note, it's still simply a C major arpeggio and a G major arpeggio.
The basic idea here is that you have 12 notes to work with. Most of the time you will be using 3 to 5 note "patterns" since these are easy to remember. Since it is on the guitar, if you learn one pattern you basically learn 12 since you can use it in 12 different keys by just playing it at different places on the neck. A piano player doesn't have that ability, for example.
If you know two 5 note patterns you can combine them to form new patterns. If many cases you'll not end up with a 10 note pattern but something smaller due to the patterns overlapping. e.g., C major = C D E F G A B can be thought of as a C major 7 arpeggio + a G7add13 arpeggio = C E G B + G B D F A or a C major 9 arpeggio + F major 7 = C E G B D + F A C E...
Or, Cmajor6/9 + Dmin = C E G B D A + D F A. The first can be thought of as the pentatonic.
With all these choices it becomes a matter of using the right "pattern" to draw your melodic ideas from. Using the wrong pattern can sound bad/wrong or very cool. The main point to get from all this is that you have 12 notes to choose from but you have to break them down into manageable pieces and understand how those pieces fit together.
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