The mitzva of ona depends on a husband’s stamina as well as his profession, as the Sages say in the Mishna: “The ona of which the Torah speaks is daily for tayalim (see below for a definition), twice a week for laborers, once a week for donkey drivers, once in thirty days for camel drivers, and once every six months for sailors” (m. Ketubot 5:6, 61b).
Some say that tayalim were healthy people whose jobs were easy and stress-free, for whom, therefore, the mitzva was each night. R. Shmuel bar Shilat is cited as an example. He taught schoolchildren near his home, his income was so modest that the king’s tax collectors left him alone, and his life was tranquil and secure (Rif and Rosh). Others say that tayalim were people who were so secure financially that they did not need to work at all, aside from some occasional management of their economic affairs that did not disturb their peace of mind (Rambam, Ri’az, Rabbeinu Yeruḥam, and Smag).
Laborers who worked locally had the mitzva of ona twice a week. Laborers who did not work locally, even if they returned home every night, had the mitzva once a week, since traveling is very draining. Donkey drivers, who transported produce from villages to markets, were generally away from home six days of the week, so their mitzva was only once a week. Camel drivers, who generally transported merchandise across long distances, would usually only return home once a month, so their mitzva of ona was once a month. Sailors, who would be at sea for half a year, had the mitzva of ona once every six months (Ketubot 62a-b; SA EH 76:5). Torah scholars, whose Torah study exhausts them, had a mitzva of ona on the eves of Shabbat, Yom Tov, and Rosh Ḥodesh (SA ad loc; MA 240:3). Some of the greatest Aḥaronim write that it is better for Torah scholars to fulfill the mitzva of ona twice a week (Me’il Tzedaka §51; Pitḥei Teshuva, EH 76:3; BHL 240:1).
A married tayal could not become a laborer without his wife’s agreement, even if his new job would improve their financial situation. Since she married him with the understanding that he was a tayal, he could not reduce the ona to which she was entitled without her consent. Similarly, a laborer whose obligation of ona was twice a week could not become a donkey driver whose obligation was once a week without his wife’s consent. Likewise, a donkey driver who wanted to become a camel driver or a camel driver who wanted to become a sailor had to ask his wife’s permission. However, a tayal who wanted to become a Torah scholar could do so due to the greatness of the mitzva of studying Torah; his wife could not protest, even though he would be reducing her ona (Ketubot 62b; SA EH 76:5; Beit Shmuel ad loc. 8).
These rulings were formulated in an age that was very different from the one we live in today. On one hand, most men work fewer hours than in the past, doing jobs that are less physically demanding. In this sense, they are most similar to tayalim. Even those who commute to work do so by car, bus, or train and are akin to local laborers, and perhaps even tayalim, as long as their commute is not terribly exhausting. On the other hand, life has become more stressful due to the competitive labor market and increased interest in news reports, sources of information, and communications media. As a result, people sleep less, which reduces their natural desire to fulfill the mitzva.
Therefore, it seems that the obligation of ona for most men is twice a week, perhaps a bit more frequent for younger people. Those whose work is particularly taxing, whether physically or emotionally, are obligated only once a week. In contrast, men who work in exceptionally easy professions are obligated more than twice a week, and perhaps even daily, like tayalim.