So first of all a little disclaimer.
None of what im about to share is confirmed, its just a pattern that people discovered, and so far it checks out for my own city.
Also i didnt discover this. Its just something i heared via fellow raiders, and i want to share it so you guys can check it out and confirm it for yourselves.
Some background info.
Pokemon GO works with S2 cells. These cells are used for easilly dividing the world map in squares. To view these cells, you can use the website Region Coverer.
Navigate to the region you live in.
For EX-raids, set the min and max level both to 12. Max cells doesnt matter.
Next draw a circel or square arround the area you wanna view (your town, city, region).
The map will show you 1 or more blue rectangles. Each rectangle is a level 12 S2 Cell.
The theory is that 1 EX-raid is given whitin each cell, assuming enough people have done 1 or more raids on the same gym.
With this information, you can determine how to easilly manipulate where to trigger a EX-raid.
If a single cell contains alot of gyms, it will be harder to trigger an EX-raid because there is a high chance alot of people raid on different gyms you want to trigger the EX-raid.
If a cell contains only a few gyms, you could raid all gyms, or just organize your group to raid at 1 gym. It helps if you already know wich gyms can have EX-raids.
For our own town, we though it was weird active raiders in the city center couldnt get 2 EX-passes with 600 raids done, but a guy on the edge of the city got his 6th pass with only 120 done total. Turns out he lives in a different cell, and theres only 14 gyms in total in that cell. A few are not eligeble for raids, others arent very accesible so we have narrowed it down to just 7. With only free passes you could do them all every week.
We are going to start our plan to raid these gyms with a few extra people starting tomorrow, so if the EX-raids keep comming every week ill have an update on this next sunday.
In the mean time i would love to hear from others if you think this could be correct.
Edit 1: New findings have shown that cells for EX-raids may actually be level 11, or even 12 (smaller) so you could have alot more EX-raids at the same time. Assuming they are all “activated” at the same time.
Edit 2: Its level 12, so changed the cells to that.