I get the feeling that we are all taking about different things. I practice regular scales, ascending and descending; sometimes pentatonic scales; sometimes different intervals; sometimes working up the neck by 1, 3, 5 notes in a particular key to facilitate movement up the neck to 12th fret. Most often though, I will practice chord tone scales (CTS) in several keys, usually G C D. This scale starts with the 1/tonic/root note and goes up 2, 3, 4, 5, (skip 6), 7, 8(octave), then down (skip 7), 6, 5, 4, 3, 2, 1. The way you use this is to play the notes of the G CTS over the G chord in a song; the notes of the C CTS over the C chord, etc. The idea is that this will give you a foundation for a bunch if things, like knowing where the melody is likely to be found and what passing tones will flesh out a run (like in embellished fiddle tunes). Its like a roadmap to improv. Pete Martin explains it better and has excellent videos w/ pdfs.