In this work, we introduce Progressive Growing of Patch Size (PGPS), an
automatic curriculum learning approach for 3D medical image
segmentation. Curriculum learning structures the training process by
presenting progressively more complex samples to the model, often
improving training convergence. In our case, we operationalize this by
starting training with small patch sizes and gradually increasing them,
which naturally improves the foreground-to-background class voxel ratio
in early training stages. We evaluate our approach in two distinct
settings. First, a resource-efficient mode maintains a constant batch
size throughout training to reduce the input tensor size and
computational cost (FLOPs) relative to conventional training. Second, a
performance mode inversely scales the batch size relative to the patch
volume, keeping the total FLOPs comparable to standard training while
maximizing final segmentation quality. Both modes are evaluated on
segmentation performance (Dice score) and computational costs across 15
diverse and popular 3D medical image segmentation tasks. The
resource-efficient mode matches the segmentation performance of the
conventional constant patch size baseline while reducing wall-clock
training time to only 44%. We show that the performance mode improves
upon the constant patch size baseline, achieving a statistically
significant relative gain in mean Dice score of 1.28%. Remarkably, the
performance mode surpasses the constant patch size baseline across all
15 tasks, while simultaneously reducing wall-clock training time to only
89%. We found that the benefits are particularly pronounced for tasks
with severe foreground-to-background voxel imbalance, such as lesion
segmentation. As a consequence of the improved convergence, the proposed
performance mode reduces segmentation performance variance relative to
conventional constant patch size training, making model comparisons less
sensitive to training stochasticity. Finally, our experiments
demonstrate that PGPS is not tied to a specific architecture but
represents a broadly applicable strategy that consistently boosts
performance across diverse segmentation models, including UNet, UNETR,
and SwinUNETR. In summary, this simple yet effective transformation of
the input sampling strategy substantially improves both segmentation
performance and training efficiency, while remaining compatible with
diverse segmentation backbones.