Disabled; takes too much space; scrolling is nice and smooth on iOS; and there just aren’t enough deep threads to warrant something that taking up so much space.

Enabled. I typical tap the top comment to collapse, but if it’s a long thread I live having the button soi don’t have to scroll up to find the top comment to collapse.

Don’t use it. Find it causes confusion.

I have it enabled and use it consistently. Surprised to hear so many people have it disabled. I like it when I’m halfway through a long comment chain and want to either go back to the parent comment or jump to the next one

Nope. Never used it in my life.