I usually do not do much post processing to my images, perhaps some exposure correction or straightening, but certainly do not spend hours manipulating my images. Sometimes people are encouraged to try various manipulations to improve an image, I am not so sure about that approach. Perhaps when you first start out you might experiment with various processing techniques whilst you learn. However I believe good photographs are made in the camera not the computer. Sure most can be improved, but not made.
The image below has had more processing than usual for me, however the difference here is I knew exactly how I wanted the image to look before I depressed the shutter. So I knew how I would process it before the shot was taken. This meant I only spent a short period of time processing as I knew exactly what to do.
The point is when you view the scene you should be able to visualize how the finished image will look and compose and expose accordingly. The post processing then becomes and extension of the creative process that is performed to finish the image. Not a process of experimentation trying to turn am image into something it is not.
I often see my images as finished prints before I take the shot. Sometimes there is not enough time, especially when shooting on the street to carefully frame each image but I still have an idea of what I am trying to achieve. I certainly do not agree with the scatter gun approach where a photographer takes many shots quickly then later tries to find one that looks good. This is simply entering a lottery and hoping to get lucky.
I would prefer to discard an image and go and shoot another one than spend hours trying to manipulate my way to an image that looks good. Sometimes you need to just abandon an image and spend what would be processing time out shooting more and improving your visualization and shot selection. You may also find you tke less shots this way.