Certainly you could spend more than an hour on one scale. by:
Playing all notes on every string and every fret available. Making certain you *know* what the note is (ie my signature block)
Playing the modes of that scale the same as above.
Additional scales, Melodic minor, harmonic minor, symetrical
I would also suggest doing arpeggios for all chord times, not just maj/min, as well as extended chords 7s, 9s, dom's and altered dom..etc
Also how's your theory knowledge? That requires study time as well.