I’m doing this today!
When I did the first gathered tier on my Coquelicot Skirt I had so much trouble! I broke threads twice and it was such slow going.
I called my relative who’s a pro and she said “it shouldn’t be that hard. Make sure you’re using good thread.”
And she was right. The thread I was using was fuzzy and some no-name brand stuff that was given to me. I switched to a polyester Gütermann thread which she suggested (anything smooth and strong and new-ish should be good). Today has been SO MUCH EASIER.
I also reduced the tension from 4 to 2 on my machine which I think helped.