When I taught that one-day workshop in Sweden, one of the questions we discussed was the number of essential skills to list in a job analysis, and by extension, the job description. Too few essential skills, and you don't differentiate your position from anyone else's. Too many, and you over-constrain the role. Surely, there must be a “Goldilocks” approach, right?
I suggested you start with three or four essential qualities, preferences and non-technical skills. Just three or four. Remember, these are essential. You can always add more desirable qualities, preferences, and non-technical skills. You want these for cultural fit.
Next, think of the technical skills: functional skills, domain expertise, industry expertise, and tools experience. Now, think of no more than three technical skills that you require as essential.
Now, you have plenty of essential skills. Plenty. More than that and you have over-constrained the position and you will make it impossible to hire.
If you are taking more than six weeks to hire for one of your open positions, review your job analysis. Do you have more than three essential qualities, preferences, or non-technical skills? Pare them down, and consider which ones are desirable vs. essential. Do not keep too many qualities as essential. You are kidding yourself, unless you are trying to hire a very senior person for a ton of money.
Do not over-constrain your job descriptions. Spend a little time analyzing your job, and you will hire fast and well.