Hacham Ovadia Yosef, in his work Yehaveh Da’at (vol. 6), addresses the situation of people who drink tea or coffee throughout the day, or night, without leaving the building, such as yeshiva students who sip hot beverages throughout the day as they learn, or office workers who sip hot beverages throughout the workday. Another example is the night of Shabuot, when people remain awake learning all night, and might be sipping tea or coffee throughout the night. Must a person in such a case recite a Beracha each time he drinks, or does the Beracha of "She’ha’kol" recited over the first cup suffice for the entire day (or night)?
Hacham Ovadia ruled that in such a case, one should have in mind when reciting the Beracha over the first cup that the Beracha should cover all the subsequent cups which will be drunk throughout the day, and he then does not recite a Beracha over the other cups. Although a beverage is digested very quickly, such that the tea or coffee over which the first Beracha is made will already have gone through the body’s system before later cups, Hacham Ovadia ruled that the rapid digestion affects only the Beracha Aharona recited after drinking, but not the Beracha Rishona recited before drinking. Meaning, in a case where one must recite a Beracha Aharona after drinking, he must do so soon after drinking, before the beverage is processed through the body. In the case of hot beverages, however, since they are sipped slowly, there is no requirement of a Beracha Aharona, and as such, the issue of the body’s digestion of the beverage is immaterial. The only issue at stake is the Beracha of "She’ha’kol," and therefore, as long as one intended when reciting the Beracha over the first cup that it should cover all subsequent cups, he does not have to recite "She’ha’kol" again over the cups he drinks later. Even if he drinks ten or twenty cups of hot tea or coffee over the course of an entire day or entire night, the first Beracha suffices for all the beverages that are drunk.
Hacham Ovadia did not address the situation of one who eats snacks throughout the day, such as one who occasionally eats apples, oranges or pieces of melon over the course of the day in the office. Here, we must also consider the Beracha Aharona, which must be recited after eating a Ke’zayit of fruit. How often must the individual recite the Beracha before the fruit in such a case?
It is commonly assumed that once a person recites a Beracha Aharona, this "cancels" the Beracha Rishona that had been recited. As such, it would appear that in the case described, one would be required to recite a Beracha Aharona each time he eats the amount of fruit requiring a Beracha Aharona, for if he waits until the next time he eats fruit, he might miss the final time for reciting the Beracha Aharona. The person then recites a new Beracha Rishona the next time he eats fruit.
This is, in fact, the Halacha. There is the surprising opinion of the Me’oreh Or, who maintained that if one recites a Beracha Aharona with specific intention not to "cancel" the Beracha Rishona, this stipulation is effective, and he can continue eating without reciting a new Beracha Rishona. However, later authorities challenged this view, noting sources in the writings of the Rishonim indicating otherwise. And it is clear from the aforementioned responsum of Hacham Ovadia that he did not accept this opinion. He writes there that if one’s tea or coffee had cooled, and he drinks a cup all at once, such that he must recite a Beracha Aharona ("Boreh Nefashot"), he must then recite a new Beracha of "She’ha’kol" the next time he drinks. Hacham Ovadia did not give the option of having in mind to keep the Beracha of "She’ha’kol" in force, clearly indicating that he did not follow the controversial opinion of the Me’oreh Or. Therefore, if a person eats snacks throughout the day, he must recite a Beracha Aharona after each time he eats the Shiur (quantity) requiring a Beracha Aharona, and he then must recite a new Beracha Rishona the next time he eats.
This is relevant also to one who drinks a regular beverage, such as water, throughout the day. If he drinks an amount requiring a Beracha Aharona, he must recite the Beracha Aharona soon after drinking, and then recite a new Beracha Rishona the next time he drinks. And thus, for example, if men are playing sports for several hours, and occasionally take breaks to drink water, they must recite "Boreh Nefashot" after each time they drink, and then recite "She’ha’kol" the next time they drink, no matter how many times they stop to take a drink.
Summary: If a person slowly sips hot drinks over the course of the day, without leaving the building, he should have in mind when he recites a Beracha over his first drink that the Beracha should cover all the drinks throughout the day. He then does not recite "She’ha’kol" again over the subsequent cups of tea or coffee. If, however, his beverage cools, and he drinks a cup all at once, thus requiring a Beracha Aharona, or if one drinks a cold beverage, such as water, thus requiring a Beracha Aharona, he must recite the Beracha Aharona soon after drinking, and he then recites a new Beracha of "She’ha’kol" the next time he drinks. Likewise, if a person eats fruits throughout the day, he recites a Beracha Aharona after each time he eats, and then recites a new Beracha Rishona over his next piece of fruit.