What is good productivity for life doesn't always translate over to poker. I have mixed feelings with the concept of poker multi-tasking. I don't preach it, but I do practice it, and I'll tell you why.
Poker multi-tasking applies mostly to online poker. It is the practice of playing a table while simultaneously web-surfing, reading emails or even playing additional tables. The cons are clear. You can't pay attention to your opponents betting patterns, you run the risk of missing a winning hand, and you take the game as a whole less seriously.
I find that there are advantages to splitting your attention as well, but they are all dependant on your state of mind and over all personality. For example, if you are a math based player, with disregard to the psychology of the game, multi-tasking doesn't hurt you as much. Players working the odds angle can be more profitable splitting their money over multiple, simultaneous tables than with a single buy-in. The theory at work here is that more games per hour decrease the chances of any one player outsmarting you for the bulk of your money.
Another personality that can benefit from multitasking is, you guessed it, the easily bored. Online poker is already faster than in-person games, but without the interaction of visible reads and conversation, it may not fit into some's fast-paced lifestyle. It is better for such a person to find diversions while they are not in a hand than for them to get annoyed, and thereby reckless, and try to rush the game.
That said, neither one of the fore-mentioned personalities will ever be able to become a world-class poker player. It's just not in them. However, if they accept that, they can still be a profitable poker player.