It depends. I lived for a short while in a little town in the midwest and was looking for a martial arts instructor so that I could continue my training. Unfortunately since all that was in this area was corn and dirt, there weren't too many qualified teachers and not too many interested students to attract the teachers. There was one Karate guy who travelled around and taught in three of the towns and that was it. I went and watched a few of his classes and I was dismayed at the quality of his Black Belts and the lack of enthusiasm shown in the class... In short, I wasn't impressed at all. After the class he came up and gave me the speil and as we got to talking he informed me that he was getting ready to be promoted from 3rd Dan to 7th Dan due to a death in his organization and the need to fill in gaps. It is my opinion that this was just too big of a promotion, especially at the quality of the instruction.
In many arts after you reach a certain level, promotions are based on time in grade and contributions to the art. If there is no required learning after, say, 4th Dan and the system was in need of higher Dans... the 4th Dan has all the information he needs and it would probably be best to promote him to a higher level to fill in the gaps. Gaps in a system are not a good thing. It makes it harder for deserving people to get promoted because those that have the authority are few and far between or even non-existant. In order to ensure the propogation of your art, you have to make sure that the gaps are filled with qualified individuals who may not have met the time requirements or service to the art requirements... those will come when they are placed in the position of greater authority.
So to restate my opinion:
Promoting to fill in the gaps is appropriate if and only if
The individual has the skill of that position but is not that rank because of a lack of time in grade or service to the art.
Gaps are important to fill because it helps keep the art alive, but if care isn't taken you can kill the art faster by putting unqualified individuals into place which will cause the members of the organization to lose respect for the governing body and potential students will be lost because of that lack of respect and the lack of respect for the rank.