To me it seems to depend on which gate opens first- back or front. Maybe they are supposed to open at the same time, but they didn’t on the day we were there.
Week before last we were near the front of the line at the back entrance to Epcot and waited for twenty minutes before they finally let us past the CMs ( it was around 8:55) and by the time we got to The Land Pavilion(and we walked fast) there were already mass crowds pouring into the pavilion. A total sea of humanity. Definitely not within 30 seconds of each other. We were two of the first from the back and hundreds and hundreds were in front of us at Soarin’.
That day, the front gate must have have had several minutes of advantage time over the back gate. It was a disappointment for us. Soarin’ was already a 25 minute wait (posted 10, but it was 25 minutes before we were on), and ten minutes after we got in line, it was a posted 50 minute wait.
I imagine that FEA would be the same. The back gate people were disadvantaged that day by the timing of entry. Makes me wonder if they randomly switch it up, or if the back gate CMs just weren’t communicating well that day.
Come to think of it, maybe it’s the new procedure where people are allowed into the front of the park to a certain point. Maybe that always gives the front of the park the advantage now? I just know what I saw on the day we were there and the back entrance was not an advantage.