Large batches of work move more slowly than small batches. Small batches get done faster and have less variability.
What is the optimal batch size?
Don Reinertsen talks about batch sizes as well as the important topic of transaction costs versus holding costs. He emphasizes that an economic trade-off has to be made in product management and explains how this applies in particular to software.
Video: What is the optimal batch size?
References
Reinertsen, D. G. (2009) Principles of Product Development Flow