@ggc You are right. Sorry that my quick reply wasn’t helpful. 
Meant to share @patdavid’s tutorial. 
Thanks @paperdigits!
Mean v median: one is not necessarily better than the other; it depends on your images. If your aim is to remove objects, then median is the way to go.
Adding to @paperdigits’s point (1), I would try not to do that much to the development of the images. The more you push them, the less effective the noise reduction blending shall be. If you are using RT, I would do everything that applies to the raw pipeline and leave everything else post-blend. You can always re-import your blended image for a second round of processing.
I mentioned enfuse because I find it that does a better job than a mere mean or median blend.