Model-based planning is often thought to be necessary for deep reasoning & generalization. But the space of choices in model-based deep RL is huge. Which work well and which don't? In our new paper (accepted to #ICLR2021), we investigate! arxiv.org/abs/2011.04021 1/ Spoiler: our findings really challenged some deeply-held assumptions we had about what planning is useful for and how much planning is really needed in popular MBRL benchmarks---even some "strategic" ones like Sokoban. 2/