Watch Timing Apps

Kello mainly gives the estimated daily deviation based on the averaged beat. It also shows a small scope view of the sound, so you get an idea whether the roller is centered. I use it all the time when adjusting watches.

The same company also makes Twixt Time. It works by taking snapshots of your dials. It then recognizes hand positions and depending on the time of the shot, calculates daily deviation. I haven't tried this one.

Also on the App Store is Watch Tracker. Sounds similar to Twixt Time but it will produce plots of your watches performance over time. I think you can also print them out.

Marc