In tGS, Egwene has Meidani channel something else, and then weave a gateway, because channeling in a certain location helps you to "know" it.

I seem to recall someone using this trick earlier in the series, though. I specifically remember an Asha'man in POD mentioning that it was easier to open a gateway in a place where he'd already made one before, and I'm certain that someone else between POD and tGS had already extrapolated from that the idea of channeling something else first to allow you to weave a gateway.

Anyway, between the two tricks, that little limitation has been rendered relatively meaningless. Still, it was nice to see the third age channelers working out these things on their own.