How many raids needed for an EX pass?

One per week is enough.

I missed the August 18th EX invite, I can count how many 2018 EX invites I've missed on one hand. Expected though, I only raided at one EX eligible gym this week--that Mawile wasn't lucky.

I just got an invite to a gym I had literally just visited for the first time for one raid a couple days ago. No badge progress or anything outside the bronze for clearing the raid.

My first ever EX raid was the weird turning point of them changing it up so people got passes from spinning the stops. Most of the passes I’ve got (only like 5 and I could only go to 2 of them and one coming up) were from doing only one raid at the place

We have 2 sets of 2 ex gyms (one park with 2 gyms at each end that are in seperate cells) that trigger very reliably, we all make sure to hit both open gyms at least once each week and almost no one misses out.

Only need to raid once. I would suggest hitting 2 or 3 ex eligable gyms per cycle though.

As long as a certain number of raids are done at the EX Eligible Gym in a specific time period (Offhand I don't remember if it's absolute number of raids or if higher level raids count for more - I think that higher level raids count more than lower levels, but I might be remembering theorizing and thinking it was proven fact), an EX Raid will spawn. And as long as you have done 1 raid in that time period, you may get a pass.

Almost every EX Raid pass I've gotten were from Gyms that I did 1 raid at - one of my first EX Raids was at a Gym I did 1 raid at, like other posters. First day I had spun the Gym, first Raid at the gym, haven't been back to it since the EX Raid because it's well out of my way.

The EX Raid I've got for today is for a Krilia raid I did at the Gym. That was the only raid I did at the Gym in the time period. So all you have to do is 1 raid at the gym in the right time period and you can get an EX Raid pass there.

As people has already said, one is enough. I once did a single T1 or T2 at a gym and got an EX pass from it.
Next week I did 4-5 T5 and missed out on a pass.

The only 2 EX passes I've gotten were for gyms I did a single raid at when I was on vacation. Unfortunately I was 2000mi away for the first and 1000mi away for the 2nd so wasn't able to make either. They definitely need to figure out a better system for these.

In my entire city we have only had one ex-raid.
One gym, one time....

I just don't understand this system. Some get dozens, people in my town have to travel far to visit ex-gyms, most of us don't bother that and have no chance to get M2

Its not how many you did, 1 will be enough.
The question is, were there enough people raiding in total to trigger an ex-raid.