In AE when it comes to connecting passengers, there is no such thing as competition.
How many connecting passengers you can fly on a route as well as what price you can charge to those passengers is determined almost entirely by your past efforts up to now, Even if I flew 1000 flights on a single route and picked up 25000 passengers per day, that fact has absolutely no bearing as to what number of passengers you can pick up.through your own efforts, both past and current.
For full-fare passengers, each route has a maximum fixed daily demand which is publicly displayed in the route configuration page.
Note however that there is no demand information regarding connecting passengers. No information will ever be displayed for such passengers.
If neither end of a route is a hub (whether created by you or a fellow alliance member,) then there are no connecting passengers, period.
The more alliance members who have a hub at one or both endpoints of a route you will/want to fly, the more connecting passengers you can pick up and the more magnified is the connecting passenger generating process.
If what you are seeking is connecting passengers, then your maximally profitable strategy is to fly the most heavily flown routes. In other words, seek out all so-called spamliner routes and pile on as many seats as you can fill. Fly everywhere to everywhere. Oh, and as most women would say, (airport) SIZE doesn't matter! ROFL
If your home country is the US, then join the alliance with the greatest number of US-based airlines.
If I had to give a name to this strategy, I would call it the Ride-Their-Coattails strategy.
since everything I have described to you is legally permitted, the only thing stopping you from making use of all this to maximal advantage is your realistic bias/conceit and nothing else.
Accordingly, recognize that in this game, there is no such thing as a spamliner. What we do isn't spamming - it's maximal efficiency seeking