Why are long and round chicken eggs considered less desirable for incubation?

Long and round chicken eggs are considered less desirable for incubation because their shape can indicate potential issues with the egg's internal structure and viability. Typically, eggs that are more oval-shaped are preferred, as they tend to have a better balance of air cell size and yolk placement, which can affect embryo development. Additionally, non-standard shapes may lead to difficulties in heat distribution during incubation, potentially impacting hatching success rates.