The advice is sold too! Unplugging is often the most helpful way to get sh*t done. Another technique I came across recently is to start off your day with production rather than consumption. i.e. start your morning writing a 500 word essay or going outside, sitting in a park, and just making those wireframes. Your day will be exponentially more productive!
As far as using index cards for wireframing, seems like a decent enough idea if you have a really small team. Doesn't really scale that well for larger teams/projects.
Additional benefit (not explicitly mentioned) is that you can test your UI/flows with potential users.
Imagine having a deck of cards with you in the pub. You could let someone navigate the app, card by card, and quickly identify the sticking points & user confusion. All without having to build anything.
Thanks for sharing, Luke (http://LukeRB.com)