If the tuner is on a channel in the same MUX as that of the next timer when the box goes into Deep Standby, then the box wakes up from Deep Standby, goes into Standby, starts the recording, finishes it and returns to Deep Standby. Just as expected.
However, if the tuner is left on a channel in a different MUX to that of the next timer when the box goes into Deep Standby, the box wakes up, does its recording on the different MUX/channel, but it neither goes into Standby while the recording takes place, nor does it return into Deep Standby when it finishes.