Dedication and single mindedness are the only two approaches that can help you in your life. If the entire energy is directed towards only one goal, then it can give more positive results than diverting your resources to many things at a time. It can also make one a jack of all trades but master of none. I think I am a right example as far as I am concerned.
When I was nearing a payout at one of the sites where I write, I was more focused towards working here so that I could reach the payout quickly and get paid too. And I got the benefit of the same. The payout of that web site was going to be my first one, so that was also a curiosity for me to reach the payout and that was a milestone for me.
However, if you are ready to work on many things at the same time, which today we call multi-tasking, that is not bad either. That keeps you in touch with all the things that you are working on. However, the speed is sure to come down as the energy is divided amongst all the things that you are attempting to complete. So, I guess, this is a thing that is to be totally decided by the one who is working on certain things and the nature of work.
If you have a team with your co-workers or your members of staff working for you, you can take time out to keep your most favorite goal as your center of attention. But not all can afford to pay to get a work done. So it is multi-tasking that is important along with the speed of your work.
If you can manage to have speed, beauty and accuracy in your work, you can certainly reach many milestones even in a short period. Just give it a try and see how successful you can be.