Dear administrators:
I am a PhD student from Univ of Oregon. We are studying the characteristics of Internet routing instability.
I have a very simple survey for the administrators. Do you mostly do the system maintenances during the weekend in order NOT to interfere network usage during weekdays? Here I mean maintenances like change routes, replace devices, change configurations...
The more response, the better 
Your cooperations are greatly appreciated!
Zhen Wu