Does a new header record have to be written for every data record generated?
No, each sensor set within a data record contains an offset that identifies the header record that is to be utilized to access the data contained within the data matrix. Sensor sets that return the same sensors and return data for periods of time in which the virtual instrument was in the same state can have identical offsets into the header file. That is, a given header record can be used by multiple sensor sets as its description of both the instrument state and to give the layout of its data matrices.