The concentration of reactants change the nature of the precipitated silver halide.
The absolute vAg (or pAg depending on equipment) determines the crystal habit (see a previous post with chart for this) and the control of flow rate of Silver + Salt to maintain that starting vAg will control dispersity.
Addition rate determines overall size and crystal dispersity as well. Shorter addition times give more monodispersity and smaller cyrstals, on average. But, it depends.
Older emulsions used initial dumps of silver. In fact, early German translations use the word "gekipped" (tipped or dumped) to describe the initial step of silver addition.