The only thing I'm worrying about is accidentally using it too much and getting rid of the callus, hopefully that's not really an issue unless I use the sand paper like above 
Hey S, it only takes a little bit of filing, especially if you're using a crystal file. Make just three or four light passes, rub your fingertip, if it's still catching, file a little bit more. Best to keep stopping and checking. Once your fingertips are smooth, that's enough.
I also find it works best to do this two or even three times a week in summer. Takes very little time. A lot of my playing is fingerpicking so I like to keep my nails similar in length, makes it easier to find the strings. Dramatic changes in nail length mess me up.
I don't have enough character to use an angle grinder
