I think there's something like rate limiting going on for Twitter/X DMs & if you fire off too many similar / identical DMs in too short a period of time, that gets you suspended.
Also I'd add a fifth lesson to your list
5) Request an archive of your Twitter/X account on a regular basis (at least monthly, maybe more often) while that's still possible to do
Also I'd add a fifth lesson to your list 5) Request an archive of your Twitter/X account on a regular basis (at least monthly, maybe more often) while that's still possible to do