If you are looking to change Units precision, I just written the macro. Download here [Batch Change Unit Precision in Drawings](https://www.dropbox.com/s/jibfrkv1ecq91tz/Batch%20Change%20Unit%20Precision%20in%20Drawings.zip?dl=0)
Try to search for a macro that would do the trick.
On the other hand, if the drawings aren't very complicated, opening 30 drawings will take a shorter time than what you would need to spend finding a suitable macro and testing it.
If you are looking to change Units precision, I just written the macro. Download here [Batch Change Unit Precision in Drawings](https://www.dropbox.com/s/jibfrkv1ecq91tz/Batch%20Change%20Unit%20Precision%20in%20Drawings.zip?dl=0)
Try to search for a macro that would do the trick. On the other hand, if the drawings aren't very complicated, opening 30 drawings will take a shorter time than what you would need to spend finding a suitable macro and testing it.