Julie Musil asked "You're a pantser, so how do you know when you've got the pacing right, and where you need to insert plot points? "
Great question, Julie! First let me qualify that my process, like everyone, is probably slightly unique. When I started I simply started with a file filled with random notes/thoughts/names/etc. and jumped right in. Lately I've been using more of a format like the Beat Sheet from SAVE THE CAT. Either way, the outcome is the same. When I have the idea, I quickly realize that certain big "events" have to take place in order to tell the story. I also typically have a good idea how it's going to turn out. There are still plenty of opportunities for surprises on the way, trust me!
These major turning points, whether named correctly or not, represent the major turning points in the story. If I have the right characters, and the right inciting incident, it works out.
It's funny how the subconscious works as well. I recall one time where things seemed to be going too fast. But I couldn't exactly stop everything, or force non-essential material in. What happened? My character did the opposite of what I expected, which delayed the inevitable for just the right amount of time and built far more tension and depth than I'd anticipated. Voila! That's what's so great about really letting the characters fully develop.
Hope that answered the question! I guess the point is that it falls into place one way or another. And when it doesn't? You can make it work.