It could happen that in some kind of way you missed out on something in the mix and of course you now hear that back in the master. You are responsible for the mix you deliver and you should always double check your mixes by actual listening to it before sending it out. Because of the analog mastering, it’s not just a matter of open the new file, click bounce and done. Everything has to be set up again (hardware doesn’t have a save button) and needs to be re-recorded, saved, quality checked etcetera. All in all, pretty time consuming.This option can only be used if we agreed upon this and when the same settings can be used again, a new mix will probably also need some adjustments and will be charged as a new mastering-job.