I do not think it is a good idea to even try to learn all of Perl. Very few of us ever use all of it. Think of Perl as a giant tool kit. Learn well the tools you need for your current requirements. Your post suggests that you have already reached this point. Use the hints other monks have provided to add tools to you kit as your needs or interest dictate.

I know that there is a down side to this approach. Occasionally you will discover a new tool and think "Wow, I wish I had known this last week." But remember, you did solve the problem and make a working program. Isn't that better than waiting forever for the day that you could do it perfectly with some seldom used tool? Never stop learning!