The excavation of tombs such as those in Luxor is categorised as "clearance" by the Egyptian authorities, presumably because one is clearing out something which was once deliberately covered up. One result of this is that foreign missions are normally exempted from the requirement of building a magazine on site to store finds, which is quite a saving.
Just because it can be called "clearance", it does not mean that the work should be carried out in a slapdash and hurried fashion, without concern for the archaeological context. Unfortunately, the excavation of tombs has long been the home of the worse archaeological techniques in Egyptology, and it has given the subject something of a bad name in the wider archaeological community, to the extent that Egyptologists are often looked on as treasure hunters. This goes back to the very early days of the subject, when getting hold of nice objects and texts was what was important, never mind the context in which the material was found. While inexcusable, it is somewhat understandable, in that Egyptologists are usually overwhelmed with material, and it is often impossible to follow the exacting standards employed by one's colleagues in prehistoric European archaeology; one expects to find more material in one's days digging in Egypt than in a whole season on the average European site! The problem with Egyptology, and with Theban tombs in particular, is that it has been conventional to assume that all private tombs are robbed and thus devoid of any important material, and can thus be emptied in a very cavalier fashion. While the first part of this premise is usually true, THE SECOND IS CERTAINLY NOT!
It is totally wrong to assume that you will learn nothing from context before you start. Thus the material has to be excavated in a way which allows the relative position of material to be accurately noted. Different techniques have to be used for shafts and courtyards.
In an ideal environment, one would cut a section through material to be excavated, to see the different stages of deposition. However, in a vertical shaft, sometimes only a metre square, this is not easy; the main reason is that the material in such a shaft is very dry an simply will not hold together if you try and cut a section through it. Thus the only practical way to work through a shaft is to take the material out in a series of layers, usually 10-20 cm deep, noting each as a separate context and recording the material and locations appropriately. We usually refer to this as an 'artificial vertical stratigraphy', and it is illustrated in this diagram:
The light grey represents the rock and where the shaft cuts through it; the dark grey shows the fill in the shaft. You can see the series of approximately horizontal slices made through the material. This way, a shaft can be excavated efficiently and yet with attention to detail.
More conventional techniques can be used in open areas such as courtyards. Here it is normal to place a grid over the area, and take layers off this, which means that material can be positioned accurately, and also leaves a section at the side of the grid which can be studied and drawn. The following diagram, based on the situation at the end of the 1996 season, illustrates the grid: