In phase-shifting profilometry, the non-standard phase-shifting profilometry combined with the temporal phase unwrapping algorithm requires fewer fringe patterns, thereby achieving higher measurement efficiency. Since fringe frequency significantly affects measurement accuracy, we analyze phase errors in the temporal phase unwrapping of the non-standard phase-shifting profilometry and further evaluates its reliability. It was found that the reliability of phase unwrapping is closely related to the allocation of fringe frequencies. Consequently, we propose an optimal fringe frequency allocation strategy. Based on this strategy, we conduct comparative experiments on different frequency combinations of non-standard phase-shifting profilometry. Then the experimental results show that compared with the non-optimal frequency combinations of the 3f_h1+2f_h2+2f_h3 heterodyne algorithm, the average error rate of the frequency combination proposed in this paper is reduced by 62.96%; compared with the non-optimal frequency combinations of the 2f_h+2f_m+3f_l hierarchical algorithm, the average error rate of the frequency combination proposed in this paper is reduced by 49.23%.