When it comes to crafting a story, your writing pace will likely look differently from other people - just by nature of everyone having different mental states, processes, and how experienced they are. My writing pace could be very different now from my pace two years ago. But to answer your questions…
This one’s difficult to answer because I jump around a lot and have had setbacks in my own life while trying to write. Longer than others I think, because I like longer stories, am trying to develop a process that works for me, and try to get all my ducks in a row.
Pretty much all my WIPs and ideas with only a couple of exceptions are 20+ episodes.
If you’re somebody trying to grow your reader base, releasing on a regular schedule is the way to go. Basically write your story in advance and then release an episode once a week or every two weeks. Others go shorter than that (both in chapter time and release scheduling), but that’s the fast track to burning yourself out.