oh, this is the classic "first cold outreach sequence" meltdown - happens to the best of us.
short version: decent sending platforms aren't stupid. They handle the balancing act automatically. New emails and follow-ups all fight for the same daily limit, and the tool queues them based on your schedule. you don't need to manually divvy up your sends between fresh contacts and follow-ups every morning. It's not a spreadsheet.
What actually happens: day one is all new names. by week three, you've got a mix - some first touches, some follow-ups to people who ignored you (the polite ones, at least). Eventually you hit a steady state where a decent chunk of your daily limit goes to follow-ups. your tool manages that queue.
With 10 per inbox per day across 6 mailboxes, that's 60 daily sends. when follow-up day hits and the queue fills, some new contacts get bumped to tomorrow. That's fine. Expected. Let the platform handle priority.
Three weeks warmup? bit tight, honestly. Standard minimum is four weeks before campaign sends, so watch your placement closely in those first couple of weeks. Or enjoy spam folder bingo.
At your volume - 60 sends across 3 domains with 2 mailboxes each - the overlap isn't going to crash your little ship. The maths gets hairier at scale, but right now the queuing logic has you covered. no need to micromanage