Woah! Nobody has time for that! I had the experience of creating my thumbnail in .PNG, but needing it to be JPG in the end to be small enough to upload yet still look nice. I didn't realize at first that having it in .PNG was going to be impractical for their settings. I also had the experience of my internet getting temporarily disrupted and having to start all over again because it wouldn't upload the last few details (like thumbnail).