I guess it depends on what they are doing at the time? I texted one of the Summit Schedulers on Thursday afternoon. She was boarding a plane and getting into her seat. Had I texted her 15 minutes later, she would not have been able to reply for hours.
Honestly, the only one who I expect to reply 24/7/365 is Lorri Kern. She will reply from anywhere in the world it seems - even on an airplane, mid-flight. When I got pulled into Secondary Inspection in Canada, that's who I texted. Everyone else gets a few hours slack from me.
Last day of the month. 3 shops, same MSC/scheduler, due that day with nice bonuses. Applied 5am, by 1pm no word. Finished all my other jobs, canceled the apps and went home. Oh well. I don't understand, though. If I were a scheduler with deadlines so imminent that the bonuses are really high, I would be checking constantly, all day, to see if anyone has applied.