DAA said:
I wouldn't exactly call this a "last minute" response, seeing as the OP clearly says, "I can't take on a work commitment with 2 to 5 days notice".
Let's overlay a Class A timeline on this:
Day 1 AM: HQ comes up with a good idea tasking.
Day 1 PM: The staff mull over it for a bit, cost it out, find the details and turn it into a tasking order. They then send it on the units to fill by e-mail, likely to a positional mailbox (+ArcticRiflesOps@Frozentown) .
Day 2 AM: Unit full time staff see the e-mail. They send the same to the Class A leadership to respond.
Day 2 PM: Administration night. Class A leadership sees the e-mail, buried among the other hundred or so that have accumulated since the last parade night. It's not a training nights so there are no troops to canvass. It sits unanswered.
Day 3 AM: HQ, having seen the "read receipt" on the original query, knows the message has been received. HQ gets antsy because the unit hasn't responded yet. Sends off a "hastener". Now, there's another e-mail in the Class A Queue.
Day 4 AM: Unit full time staff see the hastener e-mail. They send the same to the Class A leadership to respond. The Class A leadership is on night shift with their Blackberry turned off. HQ sees the "read receipt" on the hastener. Calls the unit demanding an answer. Full time staff cannot answer the query until the next training night.
Day 4 PM: Training night. Unit Class A leadership canvass the soldiers and find a taker for the tasking. The info is passed to the full time staff who inform the HQ. It's now 23h00 on Day 4.
Day 5 AM: HQ sees the message nominating the soldier to fill the tasking.
Voila! 5 days. It can be as little as 2 days if the unit has it's training night early in the week. If not, this is the usual Class A battle rhythm.