I don't remember who suggested the following idea, but many thanks to YOU!
One of the things that makes playing scales BORING (to ME) is to play from the tonic note up the scale to the next tonic note, and then back down to the tonic note. Lather, rinse, repeat ad nauseum. B-O-R-I-N-G! To ME, that is the worst possible (totally NON-musical) way to practice getting around on an instrument. I cannot recall any tune which consists solely of playing up and down a scale (but somebody at sometime probably wrote such a tune). I have NEVER practiced scales this way!
Instead, somebody suggested this variation on scale playing practice. Play the lower tonic note TWICE. Then alternate between the tonic note and the remaining notes of the scale going up to the next higher tonic note in order. Once the upper tonic note is reached, reverse the sequence and play back down to the lower tonic note. In essence, the tonic note becomes a "pedal point" (intentionally left unexplained). Try to play with an equal amount of time between every note played. No need to rush; just play the notes, LISTEN intently as you play and don't worry about the muscle memory; it comes along for free.
In scale degrees, this exercise looks like this:
Ascending:
1 - 1
1 - 2
1 - 3
1 - 4
1 - 5
1 - 6
1 - 7
1 - 8
Descending:
1 - 8
1 - 7
1 - 6
1 - 5
1 - 4
1 - 3
1 - 2
1 - 1
Repeat.
Repeat for each and every key - but not in the same session. Stick to one key per practice session on scales so as to avoid confusion.
The starting point (tonic) can be varied to be any scale degree, going up and then back down an octave. If you do this starting on each scale degree, you will have also practiced all 7 modes (intentionally left unexplained). As an aside, the relative natural minor key is played by starting on the 6th scale degree of the major key and playing up and down an octave 6 - 7 - 1 - 2 - 3 - 4 - 5 - 6. Use the 6th scale degree as the tonic/pedal point note. For example, If the major key is C major: C - D - E - F - G - A - B - C, the relative natural minor is A minor: A - B - C - D - E - F - G - A.
Playing the scale degree notes sequentially in order will provide SOME "feel" for the relative distance between ADJACENT notes, but will not help moving fluidly from one note to any other ARBITRARY note in the scale. (We all know how composers love to "jump" around in a scale. Actually, they don't, but it can seem that way.)
Think of how the chord structure often changes in a major key song. It doesn't go sequentially in order through the I - ii - iii - IV - V - vi - vii° chords. There are a lot of songs that are based on the I - IV - V chords. You have to "jump" from one chord to the next. Sometimes there are transitional notes/chords interspersed. (I'm thinking of the "standard" transition of vi - ii - V - I, which is a very common transition back to the tonic based on the Circle of Fourths - or, if you will, a descending sequence based on the Circle of Fifths.)
That ending transition phrase provides another variation to practice: 6 - 2 - 5 - 1 (in scale degrees).
You can gain even more from this exercise by imagining (as you change from the tonic to a different note) that you are hearing a little snatch of a song. If you feel like it, play the song (or at least that small section of it). Then go back to the exercise.
This kind of exercise is best done in small doses for a short period of time. I personally don't spend more than about 5 minutes doing this exercise - but I do it regularly.
There are myriad ways to vary the sequence of notes played in a practice session. All of them provide good ways to pound the relative position of the scale notes into muscle memory.
Crazy Bob