Actually, I try to use email follow-ups as a last resort. I generally use Twitter and then LinkedIn if I haven't heard back from the person in question.

Also, before sending any follow-ups via email or SMM channels, I highly recommend sharing the most recent piece by this blogger. That always pays off, especially if you create a customized image. (here's a good example: https://twitter.com/AlexTachalova/status/1001778570849587200

That's a good question, Josh.

I'd recommend a weekly follow up for a period of 8 weeks, at most. However, care needs to be taken to ensure that your copy is smart, persuasive, and value adding. It helps to embed some of your success stories/case studies + product features most relevant to the industry of the email recipient. Also, more follow-ups do not translate into higher conversions. In fact, you need to have a Sunset Policy in place most 6-7 follow-ups. It is important to walk away and not sound overly desperate since that can eventually cause dissonance.