I apply to maybe 5 companies at maximum, but I always track them in a spreadsheet with a similar functionality to this kiter app.

I just forget what the status of each application was or is. When did I apply, when was the last communication and what was discussed. I just don't want to worry about any of it, so I write it down.

I wouldn't use an app like this because I would simply create another spreadsheet when I need it again, but I can see how it would be useful even for a small number of companies to track.