Most people feel it more difficult to eat tamago kake gohan after a certain time, though it depends on an individual, because of the texture degraded by the rice absorbing water from the egg.
卵かけご飯は時間が経つと卵の水分を米粒が吸い込む為、食感が悪くなり、個人差はあるものの、大抵の人は食べにくく感じる。