Blockwise distillation search breaks at a 55% latency budget: pairwise search leads by 3.3–16.6 points
Blockwise distillation architecture search picks child networks by summing each replacement block's isolated score, an additive assumption rarely tested directly. On DeiT-S and DeiT-B, as the block-latency budget drops from 60% to 55%, the additive integer linear program begins to trail a pairwise integer quadratic program that models block interactions, by 3.3–16.6 top-1 points on ImageNet-100 after fine-tuning. The error splits into a metric part from the score's nonlinearity and a functional interaction part, dominant on DeiT-S and DeiT-B respectively; a hybrid search that ranks with single-block logits and measures only a few candidates needs no dedicated pair measurements and beats the pairwise search in 13 of 14 full ImageNet-1k settings.