I only found out about it 'cos when ds was just over 2 weeks old, I ended up back in the maternity hosptial with a nasty infection.
I had already started expressing 'cos of ds' lack of weight gain, so started using the pumps in the "expressing room" in the hopsital. It's there particualrly for mums of premmies - and also for any members of staff who wanted to express.
(it was great 'cos I didn't need to sterilise or anything - auxilliaries came in and did it for me! I also got a great supply of wee bottles for storage!)
Anyway, on the wall was posters exapling the most efficient way to express - and stating that it wasn't like feeding a baby. It may have explianed why, but I can't remember.
Depending on how much time you have, you do 8 minutes on one boob, then swap over and do 8 minutes on the other, then swap back to the first and do 5, then 3, then 2 minutes. It's also a function of your boobs and how much you are getting out of them, but by keeping on swapping over, you manage to get the maximum out.
I tihnk I got into the routine of "as soon as the flow started to slow", I would swap over.
Obviously, this doesn't apply if you are double pumping.
One other bit of advice, if you don't manage to get him back on to the breeast, is whenver he does drop a feed, keep expressing at that time to maintain your supply.
Like weegiemum, I went on to feed ds for over 12 months (weaning at 4 - our kids are similar ages ), which included going back to work f/t when he was 4.5 months old and going away skiing when he was 6 months old and leaving sufficient supplies in the freezer for the whole 9 days we were away.
However, I was able to bring back what I had expressed (in the middle of the foot and mouth crisis - but if stopped, would have been able to "vouch personally for eavety drop"! ), which stood me in good stead over the follwoing months, particualrly towards the end, when I found that my expressing started to diminish.
Again like weegiemum, I got on best with my trsuty avent hand pump. I expressed in all sorts of places: airports (travelling on business), cusomters' offices, Heathrow Express, army boot camp (work team building exercise), ski slopes - and once, when stymied by bad weather, even in a mountain restaurant - but no-one would have guessed as it was hidden by a combination of dh, my ski jacket and the table