How much hustle is right?

I follow a few daily content email lists, each with varying degrees of trying to sell me something. The three that I read every day are Daily Stoic (Ryan Holiday), Seth Godin, and Heather Cox Richardson.

I like the content from Daily Stoic and it often gives me a lot to think about, but man, he’s selling. It seems like once or twice a week, it’s mostly just a product pitch, and it gets a little annoying sometimes. Seth Godin, on the other hand, has reliably delivered interesting content to my email every day for years, but it’s only a sales pitch once a month or so, it seems (and mostly for his alt-MBA course). And finally, Heather Cox Richardson sends long, insightful analysis of the day’s political current events (with a liberal-realist sensibility I strongly agree with), with no selling at all. On the other hand, a couple of days a week, there’s no real writing content — she takes a slack day and sends a nice landscape photo instead.

Now, I’m not going to begrudge modern content producers a shot at making a living (and Seth Godin has made a lot from me over the years; I own several of his books), but it does make me think of style from a marketing perspective. If your free content is also a sales pitch, how much can you really sell before you annoy people enough to unsubscribe? What’s the sales/churn ratio that maximizes your completed sales? How do you find that balance, or do you just pick a balance and assume it’s the best?