While I realize this would eat into the total available learning time, I tend towards the "learn skills that are useful for your current job, while also spending time learning about something that interests you."
So, if your job is SSIS developer, spend time learning some of the deeper features of SSIS. But, if you're interested in, say, High Availability features, find some time to work on that, too. Sure, it has nothing to do with your day-to-day job, but it might have bearing at your next job, or you might find ways to take advantage of it in your current job.
In my particular case, I have to be something of a generalist, the "know something about everything" crowd. Backups, SSIS, SSRS, indexing, basic table design, OS management and troubleshooting, even a touch of networking. You could turn me loose on your servers to make sure that, in general, they're running happy, getting backed up right, etc, but I'd likely founder if you put me in a pure-dev role, or a pure SSIS role.