Hey edgewise! How's the rhythm book treating you? These are all great suggestions!
Here is an addition to the approaches already mentioned. The purpose of this addition is that it maintains a focus (the more focused the practice I feel it is easier to develop a stronger groove).
Take a simple grouping of notes. You mentioned that the book has a lot of E notes and various rhythms placed for the E notes.
1. Take an E major scale: E, F#, G#, A, B, C#, D#, E
2. Isolate to a small set of notes that sound melodic...like, E, F#, G#
3. Now play that set of notes over the rhythm exercises, maintaining the order of the notes at all times!
A cross-rhythmic effect will take place and can burn your brains!
Maybe that just complicated things or maybe not...I dunno...I think its fun!
