Three main interpretations exist to explain the propose of Khufu's shafts:
1) Air shafts
2) Geomethric shafts
3) Star shafts
As well as combination of two functions - air-geometric shafts; star-geometric shafts.
Air shafts
---------------
The ventilation hypothesis is very weak. The ventilation of the chamber with the help of two channels, in theory, can be carried out either (a) due to the wind, or (b) due to the existance of the pressure difference (natural ventilation). Obviously, any bends of the shafts in case (a) will be an obstacle for the wind and reduce the volume of incoming air, therefore, for wind ventilation, the most straight horizontal shafts will be optimal. Also, horizontal shafts require a minimum amount of work compared to any other option.
To implement natural ventilation (b) the inlets of the shafts in the chamber should be located at different heights - an exit for warmer air under the ceiling of the chamber; the inlet for cooler air as close to the floor of the chamber as possible. Considering that the inlets of the shafts are located at the same height, there is no need to talk about the planned natural ventilation.
The situation was somewhat changed by Al-Mamun's tunnel, after the appearance of which the natural movement of air in the pyramid became possible. Since Al-Mamun's tunnel has nothing to do with the plans of the builders, and taking into account all of the above, there is no need to talk about any ventilation planned by the builders.
Geometric and star shafts
------------------------------------------
I would like to discuss these options. Maybe someone has some new arguments.
I believe we are dealing with star-geometric shafts: the architects of the pyramid took the altitudes of the selected stellar targets at their culminations as input data and developed a geometric design into which the shafts pointing to the stars are embded as an integral part.
It is possible to make significant progress in this direction by finding the answer to the question why these stellar targets were chosen (Sirius, Orion's belt, Kochab and some circumpolar star, possibly Thuban), and not any others.
Alex.