They all knew how complicated the Protective Rune Circle is. When Riya first showed it to them, she had explained that the Protective Rune Circle basically contained several formations functions inside.
It would be really difficult for them to guess how many formation was mixed together, but each of them complement each other.
Defense, counterattack, recovery, and so on.
With so many formations mixed together, a Protective Rune Circle usually took a long time to make. Samuel also explained to them that other people's Protective Rune Circle were usually simpler compared to the one that Riya made.
As for why…
It was because Samuel could see that Riya's Protective Rune Circle had the function of replenishing mana.
