LinkedIn can be a great tool to use to build your business - if you work it strategically. Most entrepreneurs don't know where to begin or worse, think LI is for job seekers. Once you find out how to plug LI into your existing promotion efforts, it shouldn't take more than 10 minutes/day and maybe another hour anywhere in the week.
It's a lot easier than you think. If you can use what you are already doing on LI - isn't it worth the time to find out how? Learn how to make LI work for you!