Is it permissible for a traveler to combine and shorten prayers in cases of frequent travel, and does this ruling apply only during days of travel or throughout the entire day?

Whoever travels a distance estimated at approximately 83 kilometers (four burud) in a permissible journey, it is permissible for him to shorten and combine prayers. If he reaches his destination, it is permissible for him to shorten and combine prayers as long as he does not intend to stay for four days or more. If he intends to do so, he becomes subject to the ruling of a resident, and thus he does not shorten or combine prayers upon his arrival. Therefore, as long as he has not resolved to stay for four days, he is a traveler and may avail himself of the concessions of travel. But if he resolves to stay for four days or more, then he is a resident and must pray the full prayers and not combine them.