Minimum Standards: Always include a summary
TL; DR — As a minimum standard, anything you want a stranger to read should include a 1-sentence summary.
Expanding: this includes all articles you write. The summary should go at the top. It also includes anything you recommend someone to read. Recommending that someone read something without giving them a reason why is asking for a lot of trust. To give a valid explanation of its relevance, it seems necessary to summarize the content.
I recommend adopting this standard in all written communications.
I also recommend making some effort to enforce it, by asking for summaries when appropriate.
Some reasons I believe this to be good practice:
1. I often get recommendations that are not relevant, and appear to be generated by a simple phrase-matching algorithm
2. Once I begin reading something, I often get sucked in, even if it is not relevant to my original goal.
3. Providing a summary should take on the order of 10 seconds, and transmits a lot of information.
4. The summary may already transmit sufficient information on the topic for the audience, so they do not have to actually read the thing.