[123pie123]

>Voice a concern if you think a meeting isn't necessary

Correct, I simple ask if I can be excused from the meeting.

Which I find myself doing occasionally, since a lot of people do not bother looking at anyones busy/ free calender and I end up being quadriple booked

[cpeterso]

I would also recommend voicing your concerns privately with the meeting host (before the meeting). Publicly asserting some meeting isn't necessary could feel like an attack on the meeting host. Give the host an opportunity to be the "hero" who improves or cancels the meeting. You can get the outcome you wanted without looking like a jerk.