Recording FPS Shot Strings

When I use a chronograph on my Bobcat .25, I fill up to 220 Bar, record 3 magazine’s worth at full power using AirArms Fields, recording each before shot Bar and then the shot FPS. I do the same with H&N Hunter Xtreme’s. I then create a string for each pellet/magazine within ChairGun on my phone. But to be honest ChairGun displays minimal difference between each magazine FPS graphs. The paper that I used to log the Bar & FPS generally gets stored away and hardly referenced afterwards. I do similar for each of my rifles. The Bar recordings are just used to monitor for consistent pressure loss steps and to ensure that all shots are still within Reg. What l would really be keen to know is what level of recordings do others take, what do they do with the results and how much value is there in keeping the historic results. 
 
Same as Michael: I use the ProChrono and bluetooth adaptor to record my strings on an iPad (for me this is nicer than an iPhone due to the larger display) with the free App from Apples App Store. Its has allowed me to compare how guns shoot before and after repairs and modifications and gives a long term record of performance. In addition to saving and reviewing strings for each gun and pellet combination, you can also export spread sheets for more control over plotting using a 3rd party program.