Over the last 15 years, many groups have analyzed terahertz generation by optical rectification and subsequently many different expressions are present in the literature. The theory has been developed for the (100), (110), (111) and more recently the (112) crystal faces and compared to experimental results. A recent paper by Hargreaves, Radhanpura and Lewis (HRL) deals with optical rectification in zinc blende crystals for arbitrary excitation conditions. The current paper analyzes expressions from the literature to reconcile any differences. In most cases, we have found that the generalized theory reproduces the results published in previous papers with some phase shift in azimuthal angle. However, these phase shifts not only differ between papers but also, within the one paper, between different crystal orientations. As notations tend to differ between papers, the need for a generalized and agreed definition of co-ordinates and angles becomes apparent. Identifying where these corrections originate is made more difficult with some of the papers missing explicit definitions of co-ordinate systems and azimuthal angles. It has been found that the differences originate from the definition of the azimuthal angle and direction of rotation. With these differences reconciled, the general theory is able to reproduce the azimuthal angle dependence of terahertz generation by optical rectification.