@Swann 1 already gave that answer:
The only time yo use 2H-Swings is on light days (this are shadow swings. Sure they are 2-handed, but still a different animal than your usual 2H-swings) and for the non-stop swing test (which is only introduced
after working with the 32):
"The perfect swing weight for an unloading workout is 30% of your bodyweight, which is the sweet spot for power production, (...) Use the two-arm version and employ overspeed eccentrics, the shadow swing."
- S&S, Kindle Location 1416 (Chapter: The goals and how to reach them)
"Every two weeks take a kettlebell one or more sizes lighter than the one you are currently swinging. Pick a swing variation - two-arm, one-arm, hand-to-hand, mixed - and enjoy the pain.
Do not introduce non-stop swings into your training until your normal training weight is 24Kg if you are a woman, or 32Kg if you are a man."
- S&S, Kindle Location 1481 (Chapter: Die but do)
Both things are mentioned a second time in the final chapter
Simple & Sinister Summarized (Kindle Location 1547-1577) in points 7. and 10.
Even though you personally may use 2HS as progession tactic to go up in weight, they're not mentioned in the given progession examples in the book.
See pictures/charts in S&S, Kindle Locations 1429 & 1442 (Chapter: The goals and how to reach them)
Honestly I don't want to offend anyone, but lately there are a lot of questions about S&S that are simply answered by just reading/re-reading the book.
Finding the things in the book and writing this reply took me 20min, so it's not too much to ask to find the answer yourself and only ask if you still couldn't find it. (You in this context means everyone)
EDIT: BTW there's nothing wrong with 2HSs or them beeing the only swing you use in your S&S practice. It's just not S&S anymore or as Rippetoe would say: "You are not doing the program"