Yes, I think this is one of the big differences of peoples in-play experiences with skills.
One option is that the players mostly (or at least often) initiate the idea that the Medicine Skill (or whatever) is going to be useful in a particular circumstance. As long as the DM tends to run with "reasonable" player initiated ideas, then there doesn't seem to be much issue in this case about the relative usage or value of skills. The players use the skills that they want to use. The usage of a particular skill really just depends on the creativity of the players, and the desire of each player for her PC to use particular skills. When her PC has Medicine and Vehicle (Land) Proficiency every problem can be solved with an anatomy lesson and /or reckless use of a donkey-cart.
On the other hand, another option is that skill use opportunities are something that the DM "provides". In this case, frequency of skill use depends on the creativity of the DM / adventure writer in providing those opportunities, and the capability of the players to identify that a "skill use opportunity" is occurring.
Both options are Good and Correct, of course. It's just a matter of preference. And most campaigns will mix both options. The two options also have different potential problems. When players initiate opportunities for skill use, it can become difficult for the DM to anticipate the actions of the party. When the DM provides skill use opportunities, he needs to understand which skills that the players want/expect to see used.