Frequent RJ's are a smart way to go.
Airlines simply do not fly mainline equipment to places that produce depressed yields.
You do know that RJ's have higher seat mile costs than mainline equipment, don't you? And that "yield" is a seat mile measurement of ticket price?
So why would anyone in their right mind fly more expensive airplanes (on a seat mile basis) on routes where seat mile prices are lower.
Oh wait, the old high load factor on a smaller plane argument. As long as you're talking identical frequencies and demand won't fill the additional seats provided by the bigger equipment, it's valid. But for less total cost than flying 12 RJ's a day (basically hourly service), you can fly 6-7 mainline frequencies a day (every other hour service) while offering the same number of seats and taking in the same revenue.
Same revenue - lower cost = higher profit.
What you seem to be doing is what the bean counters apparently do - look at each flight in isolation. In that myoptic view, lower segment cost with higher load factors looks like a winner. In the larger scheme of things - daily capacity vs daily demand - a different picture becomes apparent.
At the very least, the peak demand periods should be mainline equipment if you're running over 8 frequencies a day. Of course, that assumes that there's the extra mainline equipment available to substitute for some of those RJ frequencies - a luxury US doesn't have.
High yield or low yield market has nothing to do with it. It should be entirely revenue vs cost - keeping the first as high as possible while keeping the second as low as possible.
Jim