No, trousers and cardis go flat packed separately first. I use the large ziplocs (approx 12"x12") for underwear, t shirts, socks, those kind of fiddly bits that can get strewn all over the suitcase! Shoes and small bag go in the personal items bag that goes under the seat. Coat/jacket I wear.
The above is not always foolproof, but works for me most of the time.