The satellite revisit time is the time elapsed between observations of the same point on earth by a satellite.
It depends on the satellite's orbit, target location, and swath of the sensor.
"Revisit" is related to the same ground trace; a projection on to the earth of the satellite's orbit. Revisit requires a very close repeat of the Ground Trace. In the case of polar/hi inclination low earth orbiting reconnaissance satellites, the sensor payload must have the "variable swath" to look longitudinally (east-west, or sideways ) at a target, in addition to direct overflight observation, looking nadir.
In the case of the Israeli EROS earth observation satellite, the ground trace repeat is 15 days, but the actual revisit time is 3 days, because of the swath ability of the camera payload.
IRS-1A is the first satellite in the IRS constellation. It was launched from Baikonur cosmodrome, Khazakhstan. It operated in sun-synchronous near polar orbit at an inclination of 99 degrees at an altitude of 904 km. One orbit around the earth took about 103 minutes and the satellite made 14 orbits per day. The 22 day repetivity ensured repeated collection of data of the same geographical area at the same local time. The equatorial crossing time for IRS-1A in the descending node was 9:40 AM.

Repetivity of 26 days of SPOT satellite means that the sub-satellite track repeats (except for slight orbit perturbations) every 26 days. Therefore, the images taken every 26 days have the same instrument view angle for any location, which is important so that the Bidirectional Reflectance Distribution Function (BRDF) differences do not influence the data. SPOT satellite also has the capability of imaging an area by tilting the view direction of the camera across track. This mode increases the frequency of observation of a specific site and the term “revisit capability” is added to address this capability. This concept is an excellent idea to image a specific area at shorter intervals than the temporal resolution of 26 days of SPOT by across-track pointing of the sensor. However, the “revisit capability” should not be misconstrued as temporal resolution (also referred to as repeat cycle). The revisit of a location is carried out at the cost of not acquiring data over some other location. Therefore, if revisit capability is exercised, it is not possible to have systematic coverage of the whole globe within specified time duration, as is possible with Landsat TM/IRS LISS cameras. This subtle difference should be understood. An excellent account regarding imaging system explained in a lucid way can be found in the book ‘Building Earth Observation Cameras’ ISBN- 13: 978-1-4665-6647-7, published by CRC press.