Any thoughts about the relative quality of SDS Drill Bits?

Living in a house built from 750mm solid stone walls and fitting a new
bathroom (an indoor one!) I've found myself needing to drill quite a lot
of holes. A 1000mm long 16mm bit from Screwfix lasts me about 3 holes
before going blunt. Actually not so much blunt, more that the tip has
just worn away. Cost per hole, about 6 quid! Are these 'cheap' drill
bits or will they all last like this. Just ordered a couple of Bosch
bits, to see if they're any better.

Also is there a correct way to drill? Should I be putting a lot of
weight behind the drill, or letting it do it's own thing. I think the
speed is constant on my GBH2-24 so I can't vary that even if I wanted
to.