Revisit time is the average time between successive opportunities for a satellite (or constellation) to image a given area of interest at an acceptable look angle.
Revisit depends on the orbit, the sensor swath, the satellite's pointing agility (off-nadir range), and the latitude of the area — higher latitudes generally see more frequent passes for sun-synchronous orbits. A single satellite may revisit an area every few days; a large constellation can revisit several times per day.
Pointing agility matters as much as orbit count: an agile satellite that can slew off-nadir reaches far more of the Earth per pass than a nadir-only sensor, sharply reducing effective revisit.
For time-critical monitoring, revisit is usually achieved by combining many satellites — often across operators. Comparing the combined revisit of different constellations over a specific AOI is a core acquisition-planning task.
It is derived by propagating each satellite's orbit (via SGP4 on its TLE), finding every pass that can image the area within the off-nadir limit, and measuring the average gap between consecutive qualifying passes.
Add more satellites (a constellation), use satellites with wider swaths or greater pointing agility, or accept a wider off-nadir-angle range so more passes qualify.
Plan a real acquisition over your area on the interactive map, browse the satellite catalog, or read the tasking guides.