Update date and time of photos taken by placing photos on a timeline and interpolating accordingly

Question

Sometimes I stumble upon a folder of old photos that don't have EXIF information and therefore have not date/timestamp of when the photos were taken.

I can go through them one by one and set an estimated datetime based on my recollection, but this is tedious to do for hundreds of photos.

I am looking for a GUI application that would allow me to select groups of photos and place them on a timeline w.r.t. to each other, after which the application interpolates the timestamp for the photos and updates their EXIF datetime.

Usage examples:

• I would select 10 photos, place them at the timeline position 05-11-2003 11:00 and the application would assume these were all taken at 11:00 on that day
• I would select another set of 20 photos of which I know they were taken in the evening of 06-11-2003 between 20:00 and 23:00. The application interpolates the datetime for these 20 photos between 06-11-2003 20:00 and 06-11-2003 23:00.

I prefer something for Mac OS and gratis, but it's not a hard requirement, I am also interested in recommendations that fall outside of these preferences.