Maximum available time baseline between VISIONS and VHS observations. Each panel shows a close-up view of the star-forming complexes, as imaged in the wide subsurvey, on top of a Planck 857 GHz map. The colorscale shows the time difference between the first VHS observations and the last VISIONS wide field, mapped onto a healpix grid with a pixel size of 47 arcmin². Time intervals of less than 3 yr are indicated in red. A distinct pattern becomes visible, depicting the complex observation strategy of both surveys.