Comment by nigma

It depends on the revisit time, spatial resolution, region of interest, cloud coverage and product type. For example Landsat 8 images the entire Earth every 16 days, Sentinel-2 revisit time is ~5 days with 2 satellites and MODIS provides daily data but at moderate spatial resolution (> 250m). We expect both the spatial resolution and revisit time to improve as more companies are launching satellite constellations.