It depends on whose photography you look at. Some of us use much more than contrast and brightness when we edit our photos.
I see some photographers, including myself add filters to add a stylized look to the photos. I think cosplay photography is often ideal for creating a style, especially when it makes the character look even more like the source it is based on. Like when I photograph characters from Final Fantasy, I use filters to make them look like computer images. I use a software plug-in called Topaz. It has many different looks to choose from, that can be customized to our taste.
The time I put into it depends on how much work I decide to do. Some images that just need brightness and contrast, and some stylizing can take 5 to 30 minutes. Some images have elements that I may choose to delete, like if there are people that got in the background, I might clone them out. Sometimes I decide to cut them out of a bland location, and edit them into so background location photo that I have on my hard-drive. This can add hours to get the edges right, especially if there is hair or fur to deal with.