If Richard Branson had never focused enough to finish actual tasks within his various enterprises, he would not be a billionaire today. It's a mistake to think that there isn't a difference between focusing on getting tasks done versus focusing on only doing one business at a time (in this case). Branson was absolutely a focuser, and he chose to focus on numerous businesses. It'd be like thinking that having more than one errand to do throughout the day meant you didn't have focus - obviously people can do more than one thing.
As an entrepreneur, I find it necessary to focus on micro level tasks to be productive and push a product forward. For example, finishing up code for a specific feature. If I fail at micro focus, nothing gets done / launched.
However, I don't find it necessary to stick to only one macro effort at a time. If I do that I feel like I'm stuck in a straight jacket. I experiment a lot and constantly take new opportunities into consideration. I don't find this macro focus variable detracts from being productive.
The key for me, is to focus on micro elements when it's time to do so, in order to be productive. After that my macro focus can go wherever I choose to direct it. I think that understanding which camp a particular item of focus falls into is critical.