Oh absolutely, it's just a guide! Trade winds blow most strongly over water so I'm only confident of their direction over water, you're totally right mountains hugely affect it. Continental wind are much more complicated, but the centre of our big equatorial continent is bound to be bone dry.

Westerlies and trade winds form "Hadley cells" of circulating air, separated between cold polar cells (the westerlies) and warm tropical cells (the trade winds). The dividing line is about 30 degrees on earth, just north/south of the lines of the tropics though it shifts back and forth. On a gasworld like Jupiter it forms continuous spirals which is why you get enduring patterns like the Great Red Spot, but on a planet it's affected by sea temperature, depth of water, shape and height of the land, etc etc.