My cell phone goes off 3 times day at semi-random times to ask me what I'm doing. If I'm just being efficient, I need to immediately stop and do something else.
I should explain a bit. Because I hyperfocus, it's easy for me to get locked into doing something completely useless with extraordinary efficiency. It takes a long time for me to realize I should be doing Something Else in order to be more effective - rather than efficient - where "effective" is defined as "moving me towards making the kind of impact on other people that I want to have." Because really, if I'm efficient and I'm lonely, then I might as well just be a robot.
This isn't as much of an interruption as it might sound. Since I keep my phone in my pocket on vibrate, all it does is buzz in my pocket, so if I'm in the middle of something I get that quick awareness check and just keep going without even pulling out my phone. (Plus benefit: people calling in the middle of a useful work sprint now actually serve to focus, rather than distract, me - I just check after I am done to see whether it was a reminder or an actual missed call.)
Am I doing something really really really well? Am I just sprinting aimlessly to fill in time by feeling busy? Or am I doing something that I really, really should be doing?