Cleaning is a very important part of the life of a priest (or miko, for jinja that have them). The article from Isë Jingū in the 27th January issue of Jinja Shinpō was about the ritual for cleaning the outside of the sanctuaries there.
The ritual is carried out on the day before the major annual matsuri, and on the 10th, 20th, and final days of each month. Six priests are involved: one negi (a senior priest), two gon-negi (also quite senior at Jingū), one gūshō, and two shusshi (junior priests — and I’m not 100% sure on the reading of these titles, because they are not used much outside Jingū these days).
The negi and gon-negi walk on the veranda of the sanctuary as part of their duties, so they have to spend the previous night in purifying retreat. The other three only have to arrive for normal purification on the day.
On the day, all six of them change into white vestments, and are purified with salt before processing to the precincts, which they enter from the north (back) gate. The negi then takes up his position by the entrance, while the other five go to the steps up to the sanctuary, and take up positions to the east and west.
The gon-negi then receive the cleaning implements from the junior priests, and climb the steps to the veranda. First, they sweep the veranda and the railing around it. Then they clean the whole area with white cloths. These cloths are dipped in buckets of water and wrung out by the junior priests, and then handed over to the gon-negi so that they can do the cleaning. When they have wiped the whole veranda and railings, they come back down the steps and kneel to the east and west.
Finally, the negi climbs the steps and inspects the cleaning to make sure that it has been done properly. When he has finished, they all leave the precincts.
I imagine this ritual takes quite a long time, because the main sanctuaries at Isë are large, and the priests are wiping the whole of the veranda down with cloths. Cleaning really is important in Shinto, so this is most unlikely to be a formality — I would be very surprised if they do not actually wipe the whole area. (They will have to go and get new cloths during the process.)
Of course, even at Jingū most of the cleaning is not ritualised. If you go, you are likely to see priests in their vestments going around the area with a broom to sweep up fallen leaves. This is part of serving at Jingū, but there is no ritual — although I would imagine there is a rota. I do not know whether any other jinja ritualise the cleaning of their most sacred areas, but then I didn’t know that Jingū did until I read this article. It is certainly possible, particularly at larger jinja, because cleaning really is that important to Shinto.