Smart Links Expert Tips
To get the most out of Smart Links' mobile feature, space your links so that a reader has a new ad every couple of screens. As a rule of thumb, having no more than one link per moderately-sized paragraph (roughly 100 words) works well on most screens, gives your reader one expanded ad experience per phone screen. You know your site visitors best and may find that a different cadence (such as 1 link / 250 words) works better (as would be the case if you have more visitors using tablets than phones.
There's no "one-size-fits-all" solution. If your links are too dense, you'll distract your visitors from your content and may alienate them. If your links are too sparse, you're missing opportunities to monetize. Experimenting and testing is the true key to success.