Unintended consequences: Why your songs got shorter and your videos got longer

These are my favorite examples of unintended consequences that I happened to walk someone through last week.

Years ago, in a coffee shop, I was listening to someone at the next table (yea, I know eavesdropping on phone conversations is bad, but people should be less loud :-P) confidently telling their friend/client, "Trust me. You need to make the YouTube videos longer - over 15 mins. That's what they prioritize. Just drag out the content." 

I couldn't help grinning. I'd recently stopped working at YouTube then, and so while I knew that person was not exactly right, they were not completely wrong either. 

It's conventional logic now among the creator community that you do better on YouTube if your videos are longer. It's why when you search for [Peppa Pig] on YouTube for you kids, the first few videos you get are either long-running livestreams or videos that are an hour long, and if you're listening to music you can often end up in a compilation video instead of individual songs. All the systems at the time were, famously, optimizing for watch time as the team focussed on a watch time goal. 

When the decision to set watchtime as the goal and optimize systems towards it, no one quite anticipated the impact it would have on creator culture and incentives (or how quickly), and the kinds of videos that would get uploaded. Everyone anticipated people would watch longer, but didn't anticipate how it would change what got uploaded, and correspondingly how that would change usage of the product. 

The even starker example is of streaming (specifically Spotify) on songs - basically top songs have gotten shorter (here's a really great podcast about it). 

And it didn't just changed the length of the songs, it changed the structure - the threat of the "skip" and the fact that artists are paid based on if a certain length of the song the streamed, meant the incentive was now to hook the listener early and keep them listening - something no one could have anticipated when working on a streaming service.

What're the unintended consequences of your next product change?