First the usual caveat: where those comments about 50-55 based on a FX camera or a DX camera? I personally like the 50mm range on FX because I grew up with that lens and appreciate it's capability and value. When I moved to DX it became a nice portrait lens (on FX it was a small group portrait and reportage lens for me).
Working distance to subject may be a result of personal comfort (for the photographer and/or the subject) and IMO is something that is subjective, format dependent, crop sensitive, perspective sensitive and just down right personal. Any of these may dictate the focal length, our if you are not particularly crop-sensitive and have a lot of pixel head-room for cropping - just shoot and crop.
Working distance can also be dictated by physical location or venue requirements. I'm thinking about crowds and the need to get close to the subject to avoid clutter; narrow streets, etc.
You don't always have a working luxury of using your first choice. With experience you learn to deal with these things as they come, but it is really important to understand your personal space preferences in working with your subjects and also to understand what may make your subject feel more comfortable: intimate vrs distant works both ways.
Roger It's still, ISO, aperture and shutter-speed, right?