Using "arecord -d 5 filename.wav" does not stop recording unless interrupted with ctl+c and produces multiple wav files after the 5 second initial file.
While I realize this has been asked before...
Multiple files created by arecord
...I have been trying arecord on a couple of different images, both Jessie on RPi3's.
Both have Alsamixer v1.0.28. (both have arecord v1.0.28).
The image at fault cat /proc/asound/version Advanced Linux Sound Architecture Driver Version k4.9.28-v7+
The good image Advanced Linux Sound Architecture Driver Version k4.9.32-v7+
I will try upgrading alsa-utils from source.
My current work-around is "sudo timeout 5 arecord filename.wav"
This sounds like the bug that was fixed in alsa-utils 1.0.29 (years ago).
As long as Raspbian stays on Jessie and does not upgrade its packages, you have to upgrade yourself.