Within the Sōtō Zen tradition, the duration of shikantaza is not governed by a rigid rule, but by the spirit of regular, lifelong practice. Rather than seeking a precise number of minutes as a goal, practitioners are encouraged to establish a steady rhythm that can be sustained over time. For those beginning, periods in the range of about 15–30 minutes are often recommended, with the understanding that the length may gently increase as physical ease and mental stability develop. The emphasis falls less on endurance and more on a posture of sincerity and attentiveness that can actually be maintained.

In more formal or traditional settings, a single period of zazen commonly runs about 25–40 minutes, and such periods may be repeated several times in a day, often with walking meditation (kinhin) in between. This pattern reflects the understanding that shikantaza is not a technique to be completed, but an ongoing way of being that can permeate the entire day. Some practitioners, especially those with more experience, may sit for longer stretches—45 minutes or more, sometimes for many hours across a day of intensive retreat—yet even there, the guiding criterion is whether posture and alertness can be upheld without strain.

Across these variations, several shared principles emerge. The quality of presence is regarded as more important than the sheer length of time on the cushion. Consistency—sitting every day, or as close to that as circumstances allow—carries more weight than heroic but sporadic efforts. Teachers commonly encourage choosing a duration that is realistic, then allowing it to deepen naturally rather than out of ambition. In this light, even a relatively brief period of wholehearted “just sitting” is understood to be complete in itself, expressing the heart of the practice rather than serving merely as a means to some later attainment.