For example I was photographing a horse show last weekend, and I have around 3000 pictures and 30 participants.
I used to do that "by hand" with a SaaS, it would take me a full day. I did talk with them to get access to their existing API, but they kept saying they didn't have an API... Stupid.
Now instead, the "generating and uploading" galeries itself takes a single command, and I can use the spare time to sort pictures, be nicer to the customers and take more pictures :)