Dadís logbook, confirmed in the ORB entry, records that the bombload they carried for Dresden on February 13, 1945 was 1 X 4,000 lb cookie, 5 X 500 lb bombs and 4 X 250 lb bombs. The use of 250 lb bombs was surprising considering this sort of ordinance was perhaps less effective than the equivalent weight in a larger bomb. Why not 2 X 500 lb bombs? Possible reasons might be:

1) A shortage of 500 lb bombs?
2) Disposing of a surplus of 250 lbs bombs in the storage facilities?
3) A need for weight distribution for the aircraft balance/loading characteristics?
4) Some sort of tactical reason such as interruption of the firefighting measures on the ground?

Reason 3) can be discarded since the sortie to Chemnitz indicated they carried 1 X 4,000 lb cookie, 7 X 500 lb bombs.
My own view is 1) and 2) are the most likely reasons but I am interested in other views on this.