People are stupid and remove things accidentally. You can partly mitigate that by adding recycle bin functionality to a samba share. 

[Our documents]
  comment = Central storage for all our documents
  path = /home/smb
  guest ok = yes
  writeable = yes
  browseable = yes
  force group = samba
  create mask = 0660
  directory mask = 0770
 
  ; recycler
  vfs object = recycle:recycle
  recycle:subdir_mode = 0770
  recycle:repository = .recycle ; directory name
  recycle:keeptree = Yes
  recycle:touch = Yes
  recycle:versions = No
  recycle:maxsize = 100000000 ; 100 metric million bytes

The action is hooked on the delete action. Pressing shift-delete won’t prevent files from being moved to the recycler, which is good.

You can then make a cron job which throws away old files: 

# Every day at 6am
0 6 * * * root    find /home/smb/.recycle/  f -mtime +5 -delete > /dev/null