> sometimes you might ask to call them instead of typing your question.
Does not explain or justify. Is not a reason. The possibility that you might ask to call has no bearing on whether or not you should start with "Hello," because if you are going to ask to call, you would be better served by just asking to call in the initial message, and if you are not going to ask to call, you would be better served by just asking your question in the initial message.
> It also might be the case there are multiple people who can answer the question, so you want [to] send out "hi" to a few of them to see who will respond right now.
Does not explain or justify. Is not a reason. Whether you are going to send the message to multiple people or only one has no bearing on whether or not you should start with "Hello," because if you are going to send the message to multiple people, you would be better served by sending your actual question. Even if you get more than one answer, you can just thank the people for their responses, if you don't manage to delete the extra messages from other people. If you are only going to send the question to one person, you would be better served by asking your actual question, so they can move the conversation forward when they reply.
> I would not send out multiple "Do you have time to hop on a call for 5 mins?" b/c then they might call me before I delete the message.
Does not explain or justify. Is not a reason. Whether more than one person might call you has no bearing on whether you should start with "Hello," because if more than one person does try to call you before you have a chance to delete the message, you are still better served by having them know why you wanted to talk, since they can better appreciate why you would have sent multiple messages and taken the soonest call, and if no more than one person tries to call you, you are still better served by having that person know why you want to talk to them before they call.
> I use IM as more informal, (AND/)OR conversations with likely back-and-forth, that may require the other person to be present to be of use.
Does not explain or justify. Is not a reason. Whether you need someone to be present to have a back-and-forth conversation has no bearing on whether you should start with "Hello," because if you do need someone to be present, you would be better served by having them already know what you might need them to be present to discuss, and if you do not need someone to be present, you would be better served by having them know as soon as possible what information you need from them.
None of your "reasons" explain or justify. None of them actually have any bearing on whether you should or should not start a conversation with "Hello." The answer is the same regardless of your "reasons." They're not even germane to the discussion, much less are they "reasons."
