I know you ask and wonder about why I was worried about a design that used 2 uA in power down mode but then had to use a RELAY to key up power to an RF transmitter. I am not surprised that you ask!! You see the duty cycle of the transmit activity was very very low. So even though it surged a lot of current from the battery it did so only like once per day. But on the other hand the customer wanted the battery to last over 1 year and after computing the total energy for the desired number of transmitter keyings the standby current draw of the system was still significant factor for the total battery life!!

I even had to make that application run on a 32.768 kHz crystal.

Michael Karas