Although I think they are planning to spend far too much time in some places, I think the "linear" approach to a big year that is being proposed is the way I would want to do it - in other words, pre-plan an itinerary that will get all the resident / regular migrant species, and look for vagrants as the opportunity presents itself. As a strategy, it's cost-effective, and likely the most enjoyable way of doing things.
However, I also think it is not way to go to maximise species count. Looking at the ABA record currently being set, the way to go is to chase vagrants and fit in regular species in-between. For example, if you decide you are going to spend a designated week on the Canaries, you will probably just see the endemics plus a few common migrants you will get elsewhere. A better strategy is to wait until there is something mega on the Canaries, twitch it, and bag the endemics while there.
The big downside is that it's a very expensive and probably more stressful way of travelling. I'm sure these guys will set the record, as they are the first to give it a proper go, but if somebody with the resources and motivation follows a more vagrant-centric approach, I think they will see significantly more species.