If you want to be responsible with people’s times, you need to justify the need for a meeting from quite a number of angles, each of which can be summarized with a simple question:
Why do we need the meeting?
Including: Is it really required that we have that meeting? Or might there be more effective ways of dealing with the matter?
Who needs to be in the meeting?
Is the purpose of the meeting important enough to justify asking for these people’s presence? But also: Will their contribution be large enough to justify their presence at the meeting?
How long does the meeting need to be?
Can we ask this much time from the people who need to be there?
When do we need to have the meeting?
Is everyone who needs to be there available at the time of the meeting? And it would be the best use of their time?
Where do we need to have the meeting?
Is it required for everyone to be in the same room (adding to their time budget if it’s a physical space)?
Doings often make it much easier to find answers to these questions than meetings. When it’s clear what needs to be done, it’s much easier to identify the people who can and cannot contribute, whether we need to gather in the same physical space and whether the product of the doing is worth spending the time.