The test is a good measure of knowledge of the regulations. Knowing the top line regulations is important in the day to day management of a site. The nitty gritty details can be looked up, but having a base line of the regulations makes decision making easier and will have a bigger impact on overall compliance. I think being able to recall this info should be a priority, so keeping the test closed book, or doing a split (closed book for top line, open book for details because you should also know where the info is that is relevant and be able to locate it in the regulations material).