I have worked in a variety of different organisations during my career to date and several had the policy that they did not actually train people up, develop or promote from within. So if you wanted to reach the next level, you would actually have to first leave them, join a similar organisation in the sector in the target position that you desired, clock up some 2-5 years experience there and then wait for a vacancy to be posted online, hoping to rejoin them. Many did not hire ex employees either, even if you left under favourable circumstances or with a glowing reference.
However, can it be a motivational problem for staff if an employer just promotes and brings in new people over their heads, who have not either joined or grown with the company altogether at the same time, or first proven themselves overtime by working themselves up the various ranks?
If you are however an internal candidate, although many employers say that the overall recruitment and selection process is made exactly the same, impartial and transparent, is the reality however that internals are always at a certain advantage as they already know you, your working style and performance, and however well an external candidate comes across, they are still an unknown quantity?
Some employers have already earmarked a promotion to go internally but still go through the unnecessary time and expense of a full recruitment campaign even when they legally do not have to, to see if they can fish in all pools and catch some last minute exceptional talent before the role is offered to the insider.