What is the specific definition of the term “most of the time” used to determine who should be counted in the household?

The full term “place where a person lives and sleeps most of the time” is actually used to define another concept, a person’s “usual residence.” If a person does not have a “usual residence,” or a place that they live and sleep “most of the time” on April 1, then they should be counted wherever they were staying on April 1.
An important consideration in determining a person’s “usual residence” concerns where else that person could or should be counted as of April 1. If there is no other place on Census Day that would more appropriately be considered that person’s “usual residence” (a residence that they will return to in order to live and sleep at most of the time), they should be counted where they are staying on April 1.