On sites we have room yes to timber / plasterboard / metals / hardcore / soils / plastics then the costs for the skips go down, on smaller sites with little room we only separate plasterboard then the rest gets sorted and recycled an the tip. We gain code points and CCS points for segregation and recycling and meets the company CSR requirements.
I went to a large tip in west London where they recycle 95% of what comes in by segregation by hand, massive operation and quite gob smacking.
Our figures for last year were less than 3% waste to landfill and that's for demolition. Construction companies really need to get their fingers out and become more cost effective when it comes to waste.