Short answer: Because Sunrise didn't feel like it.
Long answer: Pretty sure everyone has a different maximum potential Geass power level. The reason why CC has been around so long is because it's taken her a long time to find someone who had the potential to get their Geass to a high enough level that they could accept a code. Mao was close, but apparently couldn't quite get there.
In general the extent and manner of Geass' growth seems to vary from person to person (for example, Charles got to a high enough level that he could take a code but never developed the condition Lelouch's had.)
![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
ninetydegrees![[community profile]](https://www.dreamwidth.org/img/silk/identity/community.png){kind=small}
(no subject)
Long answer: Pretty sure everyone has a different maximum potential Geass power level. The reason why CC has been around so long is because it's taken her a long time to find someone who had the potential to get their Geass to a high enough level that they could accept a code. Mao was close, but apparently couldn't quite get there.
In general the extent and manner of Geass' growth seems to vary from person to person (for example, Charles got to a high enough level that he could take a code but never developed the condition Lelouch's had.)