Of course, even if the members of the Xuan Yi Sect wanted to remember a few more, they didn't have the opportunity to do so.
The limitation of memory was one reason.
The other reasons were that the pattern of an area formation was simply too complicated to memorize.
A talisman was considered a small area formation.
Even drawing a small talisman would use up a lot of mental power.
Not to mention the energy needed to draw an area formation.
It was just like what Xie Jiling had mentioned. Setting up an area formation would exhaust mental power.
The bigger the area formation, the more complicated it would be and the greater the area under its protection would be. However, it would also exhaust more mental power.
As such, even if one knew how to set up an area formation, it would be very difficult to complete the setup.
Even if one had the heart to do such a thing, one would need the energy to complete it!