Five experiments were conducted to explore the effect of task constraints on memorability ratings and on study time allocation strategies and to examine the conditions under which an item labor-in-vain effect is found (i.e., items studied for a long time are not recalled equally or better than items studied for a short time). Results show that the strategy of time allocation was influenced by the outcome of a previous memory test (Experiment 1), by the final memory test (Experiment 4), and by the total available time (Experiment 5). None of these manipulations eliminated the labor-in-vain effect, which is not due to the subjects' inability to manage the study time (Experiment 3) and which disappeared only when the time was experimenter paced (Experiment 2). Results are discussed in terms of a cost-benefit strategy. Research on metacognitive control processes has been focused on many different aspects, including human capacity to rate task and material difficulty. In particular, in the field of memory, memorability ratings have been analyzed in various forms. In this article, we refer to memorability ratings that concern people's predictions of their own performance, either before study (ease of learning, or EOL, ratings; Lippman & Kintz, 1968; Underwood, 1966) or during study (judgments of learning, or JOLs; Arbuckle & Cuddy, 1969; King, Zechmeister, & Shaughnessy, 1980; Lovelace, 1984). The main purposes of this article are to examine memorability ratings under different encoding conditions and their relationships with study time allocation strategies and—in particular—to examine the real memory efficacy of study time. An increasing body of evidence shows that people are able to rate the memorability of items accurately (Lovelace, 1984; King et al., 1980; Vesonder & Voss, 1985)—an ability considered critical for human cognition, in that it may mediate the strategic distribution of cognitive resources to different tasks (Garner, 1987) or to different types of material within the same task. In these terms, the most logical strategy is to give more attention (i.e., allocate a greater proportion of available resources) to difficult items and less attention to easier ones. In terms of the influence of time on recall, if subjects use different quantities of study time for items similar in difficulty, the items studied most should be recalled best. Instead, if subjects study the most difficult items for a longer period of time, the potentially lower recall of difficult items with respect to easier ones should be attenuated or eliminated after study.