Is it per workstation
I've not seen if this is encrypted once per workstation. It looks like the infection and ransom is running on an individual machine, if there are communal files with say 10,000 machines sharing access then I'm not sure how this would work.
Can the scumware recognise a file already 'locked' and so leaves that alone. If that is the case them theoretically each workstation could encrypt a different file with what I presume is a different key. It's no longer a case of pay your bitcoin and get your company back - assuming the file is recoverable as there was one strain recently which was a fraud and couldn't be recovered.