Skips and doubles are very similar. (4) is the same as (1) but shifted by 1 beat (it can be interpreted as a 1/16th or 1/8th note shift). (5) is equivalent to (2) and (6) is equivalent to (3), in the same way. My differentiation between a skip and a double is that a skip ends on (leads to) a down beat while a double starts on (follows) the downbeat. Generally speaking, a skip has more forward motion while a double creates a strong emphasis.
(1), (2), (4), and (5) were all written using 8 beats. This was for convenience since the beats are symmetrical and repetitive. If you want to read them as 4/4 sixteenth notes then you just need to double the rhythm.
Also, in (3) and (6), I introduced 12 beat phrases. These can be read as 16th notes in 3, 8th notes in 6 or 1/4 note triplets. 12 beat phrases are very important and will be discussed in detail later. If you do not play in 3 or 6, often, then it is important to familiarize yourself with this feel.
1. Skips and doubles are often voiced on the bass drum. So, start playing these rhythms with your main foot.
2. Play skips on one limb and doubles on another.
3. Play the ostinatos from this chapter on the bass drum and use the ostinatos from chapter 1 on your other limbs.
4. Play 12 beat ostinatos over 8 or 16 beat ostinatos.