Limiting Design Skills

As a creative person I'm drawn to many different things. I like sewing accessories and beading jewelry. But I'd like to expand to PMC (Precious Metal Clay). I think it would be a fun addition to my jewelry and to my purses. I'm thinking charms for zipper pulls, etc. I also want to learn some more skills in wirework. I like learning new things.

Over the weekend though my brother and I were talking about my business and he said that I needed to narrow it to a few purse styles and a few jewelry styles. Because if you do too much you won't be good at any of it. But if you narrow it down you can be great. I listened but I admit a part of me was disheartened because I myself like variety. I have a lot of purse patterns and jewelry designs in mind. But perhaps he's right in the beginning I should limit my selection.

I admit as an artist it is easy to have many projects started but not as many finished. I am famous for that. So I guess his suggestion makes sense.

What do you think? Should artists limit themselves to a few designs, a few mediums, a few styles, etc or can we do a number of things? What about you what do you do?