There is a unknown Weekly Badge nearby. Is it worth a detour?
As this is not obvious, here are a few hints what one can see from that badge on the map:
Fresh weeklies land in the exact numerical center of a quadrant.
If such a quadrant is also unplayed by you, but close to something played by you, it might well the weekly generated for you.
Wandering weeklies land exactly on top of a place once a badge was played. Especially a stack with a weekly on top of a badge is most likely a wandering weeklies.
When a weekly is in neither such position it has probably been played here by someone else.
The ID of a weekly is a very good indicator of its generation date. As all weeklies of all players are generated within a fairly short time interval and then one week long other stuff is being produced, the IDs of weeklies cluster well to predict the week of a weekly without picking it up.