Writers who find success with a publisher or website editor tend to continue to submit to them. That's fine. It's good to establish a presence with an editor. If they like your work enough to accept it once, chances are they'll do it again. It allows us a comfort zone and who doesn't go for that?
But be careful. You don't want to find yourself in a submission rut. I've been blessed to have stories in eleven Chicken Soup for the Soul books. I often find myself writing a piece of creative nonfiction with them in mind as a market. A monthly newspaper for seniors in Springfield, MO has accepted everything I've sent them, so of course, I'm going to continue to submit my work there. I'd be a fool not to.
It's important, however, to seek other markets and to submit to them. Step out of your comfort zone and do a little market research for publications new to you. Network with other writers to learn some good places to submit your work. When a writer friend mentions that an editor was especially nice to work with, I'm more than willing to send them my work, too.
Even when you know nothing more than what the guidelines tell you about the publication but think your work might be a fit, take a chance and send it. What's the worst that can happen? A rejection, but you can select another publication and send it out again.
Try a new market soon. You just might meet with success.