The effect of specific laboratory practices can be very significant on the outcomes of an experiment. Therefore, the Specialist Committee V.2 on Experimental Methods of the International Ship and Offshore Structures Congress decided to perform a benchmark experiment aimed at assessing laboratory practice-induced uncertainties. While the specimens were identical for all participants, the procedure to determine the outcomes was left to the expertise and experimental capabilities of the participants and their laboratories. Hence, different approaches and experimental techniques have been applied and are described in this paper. Natural frequencies of two types of cantilever beam specimens have been investigated, namely, steel and composite specimens. The composite material specimens were cut by one participant from a single panel and provided to the other participants to limit the scatter due to fabrication-induced imperfections. The steel specimens were sourced by each participant individually, following specified dimensions and steel grade. In an effort to supplement the initial benchmark, a committee member who did not participate in the original study was later provided with identical composite specimens and instructed to carry out the tests meticulously, adhering to the benchmark guidelines and to document the practical application of a promising but rather challenging measurement technique, i.e., the Digital Image Correlation, needing specific skills for successful implementation. As a result, this paper presents the influence of selected experimental setups and data acquisition, as well as data elaboration approaches on the identified natural frequencies. Such an approach allows for assessing laboratory practice-induced uncertainties.