If by "lane splitting" you mean passing stationary vehicles within the same lane then it's something I do any time I've got space. It's expected here in the UK, a lot of the time we have a designated area at traffic lights so that cyclists can get to the front of the queue for when the lights change (although many people seem to think the big green space with a bicycle painted on it is intended for the idiot in his Porsche Cayenne to get a bit closer to the lights).

If there are regular traffic lights, temporary lights for roadworks, or just a lot of traffic moving slowly, you always see cyclists and motorcyclists passing lines of stationary or slow moving vehicles over here. Every once in a while someone will position their car to make it difficult to get past them, and at times like that you see cyclists just going around them. More often than not at times like that I've had people shuffle their car slightly to make it easier for me to get past, when circumstances permit.

The main thing you need to be careful of in my experience is the passenger who is waiting to be dropped off and figures they might as well jump out here because the car is stopped anyway, rather than in 100 yards where they had originally wanted to be dropped off. It's also good to watch indicators as sometimes if there's a line of traffic approaching a red light someone part way down will turn into a driveway or some such, rather than turning at the lights.