Manipulating the Sequence
Using Shirin and Nathan's freestyle sequence as a template, here are a few things you and your partner can explore:

An infinite loop
The first is to find a way to link the end of the sequence to the beginning creating an infinite loop. As you can see:

• the sequence ends in two-handed parallel hold, both partners in a static position;
• the sequence begins with a left over right cross-handed hold, following which Shirin reorients anti-clockwise and Nathan clockwise.

Of course you could simply release your hold and re-establish it in the proper configuration, but that's not particularly elegant. Why don't you try something more adventurous, like a turn-orbit-hand change sequence instead?

Mutations
Let's say you chop up the sequence into four sections: A, B, C, and D. (It's up to you to decide where the sequence is cut.) You might try:

• Rearrangement e.g. C A D B or any of the 23 other possibilities;
• Deletion e.g. A, C, D;
• Addition e.g. A, B, C, B, D;
• Substitution e.g. A, B, C, E where E is a completely new section.

The challenge is to get them linked properly, so you'd probably need to make some modifications to make it work. You could try inserting elements like hand changes, or use different break points (speaking of hand changes, the one in stage 3 and 4 is a particularly elegant example).

Some elements and variations are conspicuous by their absence: HALO™ turn for Leads, phase changes, and anti-clockwise orbits. How about including those perhaps as sections E and F?

And if you find the repeated alternating turn sequence (stages 7 to 12) boring or dizzying, why not change the handhold levels or some of the turns into the opposing direction?

A word to the wise
Like it or not, most of us can't stop on a penny. There is this thing in physics called momentum, and it can get in the way a bit. When putting a combination sequence together, you need to be careful when you have a fast turn in one direction followed by a fast turn in the opposite direction. Do you (or your partner) have the time and means to dissipate that amount of kinetic energy and to generate it again going in the opposite direction? Wouldn't it be smoother to insert an element in between to ease the change in flow?

Other sequences
You're strongly encouraged to exhaust the possibilities of the case study sequence, to improve other people's sequences, and to create sequences of your own. Every time you do, you're exercising your ownership of the tutorial material, converting passive information to personal knowledge.
 

More Perspective Correlation
Now some bright spark learning about perspective correlation in the core section might have thought, “Hey, if there's a 1st and 3rd person correlation, what about the 2nd person?”

Okay, smarty-pants, you asked for it...

Correlating the second person perspective with the first person perspective
Makes you the ultimate partner. It puts you in your partner's shoes while you're dancing with her or him. Mastering this gives you the complete and most sublime understanding of your partner's needs: where you need to be, what you have to do, and when to do it.

Correlating the second person perspective with the third person perspective
There is a saying amongst Leads in competitive dance, “frame your partner and then yourself”. It means you should show off your partner before doing so yourself. This allows you to understand what you need to do to make your partner look good. It's particularly relevant to dance competitors and demonstrators.