Applied online, had two interviews which were informal chats. Set a case study to analyse data with a very short turnaround time. Cancelled plans to get it done. Never heard back (not even a confirmation that they'd received it). I didn't chase up either as I ended up getting an offer elsewhere but I do think it's the bare minimum to respond & give feedback if you've completed a task.

One screening interview with HR, one casual conversation with the hiring manager. One case study (given a week to complete) on analyzing a data set and then create a ppt (no need to present but they might ask questions during the final interview loop). Final interview in person was originally supposed to be four back-to-back people, and it got reduced to two because folks were out of office. All interviews were 30 minutes long.