My husband and I started our business about 10 years ago. We had (and still have) all the ingredients of a good fit for leading a business together: we have complementary skills, we work well together, we have a similar work ethic, and we have the same values.

And for the first couple of years (essentially, until we started to have a team that was empowered to make decisions), that lent itself to a terrific leadership arrangement. However, the cracks slowly began to show, and it became apparent that co-leading is not always the best setup. I now run the business and my husband has taken a step back, which works perfectly for us at this stage in our business's life cycle.

This got me thinking about the many reasons businesses do better with one leader and only one leader. Here are the biggest ones, in my opinion.

1. Avoiding duplication is impossible.

This is overwhelmingly the biggest reason that most businesses would do better with one person in charge. In the same way that you don't want your best and brightest team members to spend all their time bouncing ideas off each other (or you), you don't want to have to do that with a co-founder. In my experience, no matter how you divide up responsibilities, a decision in one leader's part of the business always has a knock-on effect on the other's.

So, what my co-founder and I realized is that keeping each other informed of the decisions on each part of the business, or collaborating where there was a knock-on impact, was extremely duplicative. It's not the kind of thing we'd advocate that our team members should do, so why would it make sense at the top? It doesn't.

2. The team was confused, and rightfully so.

No matter how hard we tried to clarify my role versus my co-founder's, it was never quite as cut and dried as we had hoped. Business is messy! Some projects don't naturally fit into one business area or another, leading to confusion. For example, my co-founder managed the finance side of the business, and I managed operations. Overhauling our financial processing system was a joint initiative.

But the question arises: who makes the calls? Both of us? Neither of us? About 40 percent of the time (and maybe more, to be honest), our team went to both of us on projects. And then another 20 percent of the time, the team needed redirecting (that is, I had to redirect the team to work with my co-founder, or he had to counsel them to come to me). It all made for an inefficient workplace.

3. Our working styles were different, so company culture was hard to form.

During the seven years that we ran our company together, my co-founder and I pretty much unanimously agreed on business decisions. We were clear on who was an expert in which area and therefore respected each other's choices. We also agreed on the company's rowing direction. That was never an issue.

However, no matter how aligned we were on business strategy, we were still two different people with different personalities and styles. Dave, my husband, is laid-back. He likes to chat on the phone as things come up. He jokes with the team and has never been much for project plans. I like clarity and order, keeping a calendar to plan for meetings, and getting my documents in advance. While the team understood those dynamics, it made finding an organizational culture elusive. Organizational culture is often formed in the likeness of the leader of the business--especially in very small companies. If there are two people at the helm, it's harder to make that work.

Co-founding a business was an awesome way to start out, and I wouldn't trade it for the world. In the early start-up years, collaboration can ensure that what you build has been pressure-tested with multiple viewpoints, can remove the social isolation of a start-up, and doesn't carry with it any of the confusion that comes when the team starts to grow. However, once you're past the start-up phase, I highly recommend established businesses really consider why they have two leaders, and if that's genuinely the best way for the business to grow.