I think it unlikely that you will convince them to reduce the number of meetings; from my experience, people do not realise that you can do with less, until they have experienced the productivity boost themselves. In my experience, requests for fewer meetings are typically turned down by people who believe in the management model that regular meetings act as engine of progress.
If it is a purely scientific rather than a "waffle" meeting, though, then I recommend, just enjoy it. That's what you are in university for, after all.
But if the meeting is really unproductive (which means, it doesn't advance neither your direct work, nor your knowledge), then this is a classic instance for "manage your manager". Avoid directly criticising the number/style of meetings. Even at more advanced stages than a PhD, one will be looked at a person that is not ready to play ball.
Rather, be proactive: By you deciding what you want out of the meeting, preparing an agenda, preparing a list of expected outcomes, and writing down a mandatory "action list" at the end (which is checked against at the beginning of the following meeting), you can focus the meetings and help organise the thoughts of your fellow participants. You have a certain control of the agenda, this way.
If you push on the action list in a disciplined form, especially if you yourself act with discipline on it, but it not acted upon by the others, it may make the others in the meeting uncomfortable and lead them, in turn, to ask for fewer meetings on their own. Plus, you will be seen as manager/organizer of the meeting, and a disorganised supervisor may actually appreciate that, if it's done in a careful way. Don't castigate others for not doing theirs, just ask them if they have done their part.