Think of it kind of mechanism-like. You get reticulocytosis if the bone marrow is pumping out lots of RBCs to meet demand. Hence, if you have blood loss, you will have reticulocytosis. Things that would cause this
Blood loss
Hemolytic anemia
Increased Erythropoeitin, either exogenous or endogenous
Any type of anemia where the production of RBC precursors is impaired (like iron deficiency) would not result in reticulocytosis because the body is incapable.