[stinos]

Not entirely. It's more likely some human intervention is needed somewhere in the process to select the image/install containing Firefox. Although it's likely something like a checkbox, or maybe fysically selecting another disk - 16.25 seems a bit steep for that, yes.

[friendzis]

It actually does require a chackbox - customer checks it when ordering ;) Booting computer and manually installing OS/updates requires quite a bunch of [man] hours (given that they ship a bit more than few PCs a day when distributing a batch) so it is safe to assume they do not do that, but instead clone disks. it is most likely that master is kept up to date by a script.