The compose key is also useful outside of programming environments: I'm german but still prefer english keyboard layouts for easier access to several characters

The compose key is also useful outside of programming environments: I'm german but still prefer english keyboard layouts for easier access to several characters (like {}[]\ and so on) which require the use of Alt Gr on german keyboards. The compose key still allows me to use german umlauts like ä by typing <Compose>"a. I've gotten quite fast in doing that because by having compose on Capslock, I can use two fingers of my left hand to press the Shift and Capslock keys (nearly) simultaneously, one finger of my right hand to press the ' key (which, together with Shift, gives me the ") and then press a afterwards.