What do House Boats and Swiss Army Knives have in common? They are monuments to compromise, and they are third rate at every functional task. They exist because they occasionally serve a useful purpose.
Some employees are like House Boats and Swiss Army Knives. They may not be excellent at anything, but they can be adequate and useful in some ways. Do you have any in your organization?
House Boat
A House Boat is a lousy house and a lousy boat, but a small group of people own one for a variety of reasons. A House Boat in your company 
is anyone who has a hyphen in their job title. When you combine two completely different jobs into a single position, you pretty much ensure that person will be sub-mediocre at both.
A common House Boat is the Selling Sales Manager. In theory, it makes perfect sense. Get out and make sales on your own, then supervise and guide the others so they can succeed as well. In practice, it almost never works out long term.
Why? Because exceptional success requires laser focus and specialized skills. 
Alternating between two roles, two goals, and two priorities is the opposite of focus. Specialized skills are learned when you specialize, not when you generalize. "The man who chases two rabbits catches neither" - Aesop
Furthermore, great managers succeed because they build and develop the people they hire and supervise. When they sell directly, they are competing with their team. Competing for leads, opportunities, accounts, and time.
Here are some common House Boats:
- Engineering & Service
- Finance & Operations
- Human Resources & Marketing
Swiss Army Knife
A Swiss Army Knife is a House Boat to the extreme. There is always someone who is good at in a lot of areas and is willing to do the company dirty work. Like the Swiss Army Knife, none of the tools are particularly good, but they sure do come in handy sometimes.
I worked with a person one time who performed all these jobs during a week:
- Contracts
- Pre-Sales Engineering
- Human Resources
- Consultant Liaison
- Contractor Database
None of these jobs was big enough to warrant a full time person, and none was glamorous enough to attract interest from other employees. I called this person "The Plumber", because he did all the messy but necessary tasks within the company.
A Swiss Army Knife Not can be extremely useful to the company, but it's often career suicide for the person. Not surprisingly, my friend was eventually pushed out of the company because he did none of his five jobs with particular distinction.
The "Tweener"
Another variation on the House Boat is the "Tweener". These people are talented in two areas, but don't excel enough in either one to be a high achiever. A common "Tweener" is the person who is too "techie" to be a good salesperson, but too "salesy" to be a good tech.
Trying to kill two 
birds with one stone is recipe for mediocrity. Don't do it with your job descriptions.
There may be times, due to staff turnover or transition, when you need to have someone cover two jobs at once. That's expedient. Just make sure these assignments are short term and have a clear end game for the person and the company.
