Why do you only experience 8 lunar phases?

Answer 1

Because those are the eight points and shapes, during the constantly changing

appearance of the moon, to which we have given names. If you watch the edge

of the bright portion of the moon for a while through a small telescope, you'll see

that it's moving continuously, and so the actual apparent shape of the moon is

changing continuously ... literally minute to minute.

Answer 2

You only experience 8 lunar phases because the Moon's cycle moves through these 8 phases: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, and Waning Crescent. These phases occur as the relative positions of the Sun, Earth, and Moon change throughout the lunar cycle.