It's common practice here in Australia too. Weed can be pretty pricey and mixing it in a joint can just stretch it out for longer. I get 1g for $10 and I work without much financial responsibility, so I smoke it straight (also get the "badass" reputation sometimes), but my dealer is quite a slow-ass and sometimes I'll need to mix to make the last few grams last until a new "shipment."
Same, Im in Hong Kong and the Brits here only smoke hash and tobacco. The reason is that the weed they get in the UK is so shit, as is the hash but they don't know any better. Found a dealer here in HK who gives me Cali grade bud though so Im happy Sent from my iPhone using Grasscity Forum