It depends on the need of the person, like a normal person may require 3 meals a day on an average.
A malnourished child may need more meals initially to normalise.
Generally its recommended to have at least 4 doses . But someone may need only 2 doses and someone may need more than 10 doses too.
Its not about time frame, its about energy consumption, thats why its advised to spread the dose throughout the day.
In emergency like high fever, high blood sugar level, the energy required is more, so its suggested to be taken every 10 to 15 min.