not during testing, no. too easy to cheat.
during classwork or freetime though, i think it should be allowed so long as it isn't disruptive
this
Kind of related: my high school had this thing where basically every wednesday, instead of having homeroom for 15 minutes between 1st and 2nd period, we'd have our first period moved ahead a half hour, and then no homeroom between. That first half hour, instead of first period, it was just...nothing. It was still considered school hours, so we had to be there on time and everything, but there was nothing to be there for. And since it was still considered school hours, all the regular rules still applied, like no listening to music, even quietly with earbuds