Most people I know do it via some form of API integration with desktop photo managers. Lightroom/Aperture plugins come to mind (I think it's built-in to Lightroom now?)
The trick is also that most photo sharing sites don't actually have a good way to manually upload photos. Most (see: Instagram, Facebook, etc) excel only when you go through their apps.
The trick is also that most photo sharing sites don't actually have a good way to manually upload photos. Most (see: Instagram, Facebook, etc) excel only when you go through their apps.