Sometimes, if I'm making a huge post with lots of embedded stuff in, yeah. I also type with tags, so the preview is a good way to make sure they're all closed properly and the message is formatted correctly.
When I'm just posting text, no. When I'm adding quotes and spoilers and otherwise making a post with formatting, yeah usually. Not previewing this one for example and send
As others have stated, if it's more than two sentences I hit preview, even if the post still only consists of text.
I always proofread and edit what I write however, sometimes multiple times, it's just ingrained in me.