(Update ~ the reason I wanted to show where I used a split chain is that years ago, after I learned the split ring and the split chain, I didn't know where to use them! This is just one example but hopefully, it will help you see possibilities in other patterns.)
I still haven't finished rewriting the bookmark but that was because I ran out of thread on my shuttle and out of steam in my energy stream at the same time. LOL! I did want to show how I figured out how to do this all in one pass. In the original butterfly body, you had to cut and tie and then join in the middle of the chain loops. I realized I could make a split chain at this point where the second part joins and then finish the first segment on the return trip. In this scan, I labeled the first split chain and you can see that I continued on down and then came back up the other side. The second split chain happens in the same place basically, where the chain loop would normally be joined into from the lower body.
This scan shows the second half of the split chain completed and you can see it's now in a position to continue with the chain loops around the remainder of the upper body. The second half of this split chain is actually making the first part of the 5-5 chain loop so the next element is to complete the second part of the loop and join.
Here's the second half complete and from here I'll do the normal 5-5 chain loop, joining to the next picot. I'll end up at my beginning point and from there, do the entire segment again in the opposite direction. I do need to work on a way to stabilize that jumping off point though. In the first one I tatted, I added a little chain segment and then connected there but I haven't done that this time since I changed something else in the beginning ring.
Here are some sites where you can learn how to do split chains:
Fast & Easy split chain by Marie Smith
Original from Jane Eborall
Another from Snowgoose
The only tutorial I found for needle tatting but the graphics are broken.
Update: The current site for needle tatters is
http://needletatting.proboards.com/index.cgi?board=splitrings and you do have to register to access the files. Thanks to Shannon for the link!