Sometimes bread machines can be tricky. We were trying to help a customer whose bread did not rise enough. It seemed that he did everything right. Come to find out, he had an older model and a brand that we were not familiar with. (Bread machines are becoming more standardized but there are still different requirements for different machines.) So we tried to help him fine tune his mix to work perfectly with his machine.
Fine tuning may be required either because the mix does not perfectly match the machine or because of environmental conditions in your kitchen