I used polarizers a lot when shooting landscapes with film. Somehow, the effect is different is not the same on digital sensors. I still use them for removing reflections from water or deepening the colour and filtering out haze in the sky, if the effect improves the image. Sometimes it is useful for taking reflections off foliage but in many cases the difference with/without a polarizer is minimal, or the filter has a strange effect of lowering contrast giving a muddy effect. I now use polarizers much less than I used to, but they are still useful sometimes.