so ive been playin guitar for around 7 years and taught myself mostly thru friends and the interweb. im wondering how to switch between scales during a song. say im playing e minor can i switch to e major without it sounding too off? what about e minor to f minor? or e minor to a minor since theres only one note thats different? i'd really like to know because this metal band im in right now likes to bounce between different scales pretty much every riff...is this a bad thing? should we be using the same scale throughout most of the song?