The typology of stress systems shows asymmetries in the directionality of iambic foot paring. Under Optimality Theory, such asymmetries have made some analysts attracted to the asymmetric application of alignment constraints, dispensing with the constraint A_LL-F_T-R and keeping only the constraint. A_LL-F_T-L. This study contends that there is a close correlation between the size of minimal feet a language allows for and directionality of alignment constraints cross-linguistically. Focusing on the typology of directionality in unary and binary stress systems, this study tries to show that asymmetric alignment approaches are typologically untenable, considering that the unary systems put top priority on exhaustive foot parsing into prosodic words and as a result, symmetrical foot parsing directionality is indispensable. Binary stress systems showing iambic footing asymmetries, however, place value on achieving eurhythmic goals because the unattested right-aligning iambic patterns include unfavorable initial lapse. Iambic asymmetries are explained by the interaction of *LAPSE constraint with symmetric alignment constraints. The typology of bidirectional stress systems, although they are rarely occur, also gives support to the mutual relation between minimal foot size and alignment directionality.