I started posting my True Power series in 2007. I'm not sure how long before then I started working on the series. The comic and all side stories were completed in 2016. So that took about 9 years, minus a 2 year hiatus (do not recommend, ever).
I started working on the story for the sequel, True Power: MS2 in... it must have been 2008 because I was still in college. I finished the thumbnails... I'm not sure when. I'm pretty positive before I started posting the comic. I started posting the comic in 2017. It's been 3 years and now I am on chapter 8 out of 20. Maybe 40% done. Ooph, kind of a scary number. Wish it were higher. lol
For my main comic, Celestial Chronicle Shion, I'm pretty sure I started brainstorming and creating the story in 2016 and started posting in 2017. 3 years later, I'm about 25% done.
Much of the process has remained the same as I thumbnail/outline in a notebook, review and tweak as needed. However, I used to work with traditional materials and now work digitally.
The things that have changed are I have more of a drive to work faster and complete more. I want to get faster at drawing so I can increase the output.
The stories are all my original vision for them.
I also have a new story I am brainstorming and want to begin working on but I really want to complete my True Power comic before working on it because 2 comics is a lot to handle already.