This study investigated the effects of two different planning time conditions (i.e., operational [20 s] and extended length [90 s]) for the lecture listening-into-speaking tasks of the "TOEFL iBT"® test for candidates at different proficiency levels. Seventy international students based in universities and language schools in the United Kingdom (35 at a lower level; 35 at a higher level) participated in the study. The effects of different lengths of planning time were examined in terms of: (1) the scores given by ETS-certified raters; (2) the quality of the speaking performances characterized by accurately reproduced idea units and the measures of complexity, accuracy, and fluency; and (3) self-reported use of cognitive and metacognitive processes and strategies during listening, planning, and speaking. The results found neither a statistically significant main effect of the length of planning time nor an interaction between planning time and proficiency on the scores or on the quality of the speaking performance. There were several cognitive and metacognitive processes and strategies where significantly more engagement was reported under the extended planning time, which suggests enhanced cognitive validity of the task. However, the increased engagement in planning did not lead to any measurable improvement in the score. Therefore, in the interest of practicality, the results of this study provide justifications for the operational length of planning time for the lecture listening-into-speaking tasks in the speaking section of the TOEFL iBT test.