def _should_accumulate(self) -> bool:
        """Checks if the optimizer step should be performed or gradients should be accumulated for the current step."""
        accumulation_done = self._accumulated_batches_reached()
        # Lightning steps on the final batch
        is_final_batch = self._num_ready_batches_reached()
        # but the strategy might not
        strategy_accumulates_on_final_batch = self.trainer.strategy.handles_gradient_accumulation or not is_final_batch
        return not accumulation_done and strategy_accumulates_on_final_batch
Checks if the optimizer step should be performed or gradients should be accumulated for the current step.
src/lightning/pytorch/loops/training_epoch_loop.py