Generally I tend to stick with worsteds and flannel for suits, tweed for odd jackets, and flannel for odd trousers. I would say that there are many exceptions such as the navy hopsack as a sport coat, even though it is suiting, or tropical weight worsteds for warmer weather odd trousers. I think color also divides fabrics use, such as greys being used for full suits or odd trousers but not as jackets, and blues being used as jackets or full suits, but not as odd trousers. Brown being a quitessential sport coat color, etc. Pattern also plays a big role, such as POW which when in a small scale as a worsted is pure suiting, but as a tweed in large scale in brown with an overcheck is jacketing, all depends on the cloth type, color, pattern, scale of the pattern, etc.