I've just noticed during today's Tuesday grid roll, at least for LearningCenterDT, that while the restart timer is active, new user accounts are still being dropped in.
I recommend that for the duration of the roll, any welcome-type region on the channel being rolled should not be accepting any new or very young accounts. As a new user, it would be highly discouraging as your first experience of the platform, to get a big scary screen shake, a loud alarm sound, an unremovable timer, and getting booted out when it reaches zero, without even knowing the slightest thing about what is going on.
If a new or very young user decides to teleport manually into a welcome area region that is still to be restarted, a scripted message could be sent in friendly language that notifies the user of what might happen if they hang around for too long.