Digital services are by their nature a unique kind of media, unlike any before. They enable both interactions between humans and technology, as well as interactions between humans - mediated by technology.
In both cases, all these interactions happen in time. This unique interactive nature of digital means that the effectiveness and quality of the service it provides is a function of time. But that's not all.
I believe that the real long-term value, adoption, and commercialisation of digital services happen at the intersectionof time (a human resource) with another powerful human resource - attention.
Time spent on an interaction is quantitative, but the value derived from that interaction is about the quality of attention that the digital service demands.
Take a digital product like a Map, for example. When used in 'searching for address now' mindset, it delivers more value the less time and attention it takes up from the user. The user is on the move, probably walking, driving or cycling, maybe coordinating on the phone with a friend, maybe carrying something ... it's a resource-poor context. The user does not have much time or attention to spare, as it is taken up by so many other demands. So the lesser she has to refer to the map, and the less mental attention it demands from here to reach her destination, the more effective and valuable it is perceived to be. Attention is a result of the cognitive load demanded by digital products.
The 'usability' mantra in modern digital design is anchored in the idea that digital products should take up as less cognitive load as possible. But that not necessarily true. The real answer on how much time and attention a product should demand is: it depends.
Let's take another Map example. When the same user as above is in, let's say, 'discover new restaurants for this evening' mindset, she is engaged at a very different level of time + attention. She is probably less mobile than before, more relaxed, and therefore willing to invest more time and more attention. At that point, a map service would do well to adapt to support her current resources. Pinterest Maps does a wonderful job at addressing this mindset and supports the user in 'discovery' mode by allowing browsing, bookmarking, connecting, sharing.
Every digital interaction is an evolving negotiation, an emergent dialogue, between the user and the technology. One of the core aspects of Behaviour Design is about matching the behavioural resources available from users to their expectations, and the consequent 'perceived value' delivered by the digital service. And monetization by a digital service is a direct consequence of the how it handles that value at the intersection of time and attention.