I love this stuff.

We started off with Catsan as thats what thte kittens were used to, but then switched to Oko Plus.

When I do a full litter change I do make sure it is very full of clean stuff, nice and deep, just so I don't have to top up every time I scoop.
I was originally doing a full change / tray wash every week, but being honest it really didn't need it so I've cut down to once every 2 weeks. Obviously I still scoop a lot and I am really anal (no pun intended!) about getting out all the dirty bits! The week I'm not changing it I usually top it up.

A bag will last me about month like this, maybe 5 weeks, with two kittens. That's the normal 10litre bag - I'm hoping to order a 40 litre abg at some point, as that should work out so much cheaper.