Worst application experience I've ever had: First round interview was to understand my experience, second round was a technical quiz. I passed both and then the hiring manager scheduled a group interview after completing a take home project. I started working on the project (which was very broad - all they wanted was an hour long presentation on a topic within data science) and then five days later I was informed (on a Monday) that they had gone with another candidate on Friday, without even hearing the presentation I had been working on. Incredibly unprofessional behavior.