LinkedIn outreach - how many follow-ups are too many?

I'm currently starting out doing outreach on LinkedIn in the mental health tech space.

I'd love to get some advice on when to stop following up and how much follow-up is reasonable in different situations:

- When they haven't seen any of my follow-ups (2-3 messages) at all

- When they've seen the messages but haven't replied (I usually try switching angles and probing their current situation in my follow-ups/initial outreach, until I get a reply)

- When they replied to previous messages but then disappeared, even after follow-ups.

- When I've sent a calendar link, followed up once, and then they ghost me

I don't want to waste too much time on leads who aren't interested, but I also don't want to annoy people with too many follow-ups.

How do you decide when to stop? And if you do, what do you usually say in your last message?