JanBB,
I have stop sterilising the bottles everyday for >1 month already. Now only sterilse once a week. My experience is once baby drinks up the milk, rinse the bottle immediately with boiled (cool or hot) water, bottle will be very clean, ready to be reused. But if you leave it longer, then residue may build up at the site of the bottle (I am using Avent btw), and difficult to make it clean, need brush to get rid of it. The longer you leave it, the worse it goes.
Sterilisation seems to be a very easy task. Since I stopped sterilising it everyday, it actually makes me feel A LOT more relax at night. I have 1 less chore to do, meaning more time to be with Hao Re, and more time to myself.
Or if you are worry, for travelling, get sterilisation tablets.