how many follow-ups before i stop, and what does the last one actually say

Three touches, all in the same thread, spread over about twelve days. Your instinct is right and the four to nine advice comes from people mailing thousands of strangers, where the marginal cost of annoying someone is zero. On a hand picked sixty it is not zero, those are the same sixty you want to talk to next year.

What has worked for me is making the ask smaller each time. First email asks for a fifteen minute call. Second asks a single question they can answer in one line. Third says I will stop here, if this is ever relevant my details are below, and nothing else.

Roughly half my replies come from the first, a third from the second, and the rest from the last one. The last one earns its place, but only because it genuinely is the last one.

Three. Same thread. Smaller ask each time. Then take them off the list and mean it.

Do the arithmetic before you tune the cadence, because it tells you where the problem is.

Sixty targets at three touches is a hundred and eighty sends. At a healthy reply rate for a well researched list you are hoping for somewhere around five to eight replies, of which a couple become calls, of which maybe one goes anywhere. That is the honest shape of sixty targets, and no follow up schedule changes it much.

So the lever is not the number of touches, it is the size and quality of the list and the first line of the first email. Two replies from sixty is not a disaster on week one. Zero from sixty after all three touches would tell you the message is wrong, and adding a fourth would only mean being wrong more often.

The compliance shape, because it is easy and people skip it. Commercial email in the US needs a functioning way to opt out and a real postal address on the message. Europe and the UK are stricter about consent and business to business cold email leans on a legitimate interest argument, which among other things means you have to actually have a reason this specific person would want it.

In practice both come down to the same two things: one plain line at the bottom saying reply stop and I will remove you, and honouring that the same day. It costs you nothing, it makes the email read as more human rather than less, and it means you are not building a list you are afraid of.

Something small that doubled my replies and cost nothing: I stopped attaching anything and stopped including a link in the first email. Just plain text, four sentences, one question. Links and attachments make it look like a campaign, and people can tell in half a second. The link goes in email two, once they have replied or at least opened twice.