In my crochet shop I intended cowls, fingerless gloves, scarves, beach wraps, baskets, coffee cozies - well, anything I can crochet.
However, I was selling crochet in this shop (and another I closed when I created CrochetSewEtc) and a trend of its own evolved for me - turns out certain items are moving, requested for custom orders and I have received high praise soooo...think I will be focusing on three products.
When I get bored I may veer off to some other items to mix it up but I can do a lot of variations with what I'm choosing to stick with so don't know that I can get bored. :-)
Basically, follow your muse and if your customers or products pick a specific direction for you, so to speak, consider following it if it works for you.
ETA - three product lines - many variations. Not three products.