It takes up to six working days to place the company's inflight magazine in the seta pockets just right, and due to union demarcation concerns this can not be done at the same time as placement of safety on board cards.
At Air NZ it takes at least a week to get the hobbit hair (mostly foot) out of the carpets following shooting of each "epic" safety video. It could be worse, seats used in Bear Grylls videos must be burned then buried in quarantine waste facilities, under MAF supervision.
The IFE content has to be loaded and checked, with company personnel watching each programme in full from each seat. This in turn may require further carpet cleaning as above, depending on staff hirsuteness.
Functional checks of cabin interiors include checking true and representative images of each and all genders in each bathroom mirror and trial flushing of variety of substances into each on board lav. This of course takes time and the assistance of the Air NZ catering department 12-24 hours prior.
Also a day or so for pilot/cabin crew/engineer and ground crew familiarity and training, checking compatibility with procedures, GSE and terminal equipment, including "shakedown" precipitating likely in-service failures.