They are two tabs on the same screen. Quick is right when you want a post and you want it now. A session is right when the post matters enough to work on — a launch, a pinned post, something a client will see.
"Make the cover punchier." "Shorter on slide three." "Try it as a Myth vs Fact." You are talking about the post in front of you rather than describing a new one from scratch, which is the actual difference between refining and rolling the dice again.
Every version is kept and every one is still openable. This is the part a regenerate button cannot do: the third attempt is often worse than the second, and without a thread the second is gone.
Pick any attempt in the thread and make it the active one. Export from there. Nothing is lost by exploring, which is what makes exploring worth doing.
The winning attempt behaves exactly like a Quick post — every size, the caption, a zip, or an MP4. A session is a way of arriving at the post, not a different kind of post.
Both are right. They are right at different moments.
Topic in, post out, roughly twenty seconds. Most weekly posting is this, and treating every post as a project is how people stop posting.
A launch, a pinned post, a client review. The cost of a bad version is high enough that being able to go back to the good one is worth more than speed.
A session post and a Quick post never merge into each other. Which mode made a post is recorded when it is made and never changed afterwards, so a thread cannot be rewritten from underneath you.
One throws the good version away. One keeps it.
The dashed one no longer exists. You are one click from losing the version you liked.
All three are still openable. Exploring costs nothing, so exploring is worth doing.