i used to bring a bunch of them wherever i travel. but nowadays i just rely more on raws and bracketing.
filters get scratched easily and you lose picture quality when they do. plus you need to deal with reflections and such.
no point lah.
Not just landscapes, there will be some street shots where a filter comes in handy as well.
The last i went europe with my gf didn have much time to setup tripod and bracket the shots i want to bracket, GND was a convenient way of stopping down the brightness of the skies. Not all scenes and shots are suitable to be bracketted as well.
With proper care and handling the GND filters shld last some time. I cannot extend this comment to every makes and brands. While it is time to change new filters, you would have shot your worth of keepers