I don't understand: why not the classic `watch make` (watch defaults to 2 seconds)?
Or watch -n 0.5 make does the job too
Not always:
$ echo $LANG
pt_BR.UTF-8
$ watch -n 0.5 false
watch: failed to parse argument: '0.5'
You can literally write it as a shell script
#!/bin/bash
N=2
while true; do
clear
echo Every $N\s: $*
$*
sleep $N
done