It takes between 2-5 hours to do one. They are all copyrighted and posting them in a public place like here secures that copyright. Watermarks are useless and easily removed.
I have a team of lawyers that look after my stuff and makes sure they aren’t being used for profit without my permission. I have taken down a few infringers, but generally I haven’t had much of a problem. It is hard to use these low resolution forum images for much beyond personal use and I usually don’t care about that usage. Try to print them at any decent size from an image taken here and it will be a fuzzy mess.
I also hide non recognizable IDs in each image that only show up when I adjust the image a certain way. Copy my image and I can easily identify it with a few simple adjustments.