Practicing in 4ths or 5ths is better/easier because the chords, progressions and scales don't change that much. There are just minor changes between a 4th or 5th interval. I practice everything this way now, but I also practice moving chords and scales along an arpeggio...meaning taking a chord like a CMaj7, breaking it up into its fundamental parts and using a totally different chord or scale along those notes. I've found that this presents some interesting ideas.
For instance...
Key Cb
(A Maj3 interval broken into a arpeggio, descending along a CMaj7)
C-E-G-B \ B, Eb, G, B, E, Ab, C, E
Cb-Eb-Gb-Bb \ Eb
or
Key G
(Maj chords played along a CMaj7)
Ab-C-Gb \ EMaj, GMaj, Bdom, CMaj
A-E-G \ GMaj
written out
Ab-C-Gb \ B-E-Ab, D-G-B, B-Eb-Gb-A, C-E-G
A-E-G \ B-D-G
You get the picture though....I'm still learning this though.