Get an actual job in the domain and you'll quickly discover all the pain points. For example, become a medical physicist or dosimetrist and try working in a cancer clinic. Asking to shadow random medical professionals won't work well unless you have a friend on the inside greasing the wheels.
This is great advice because it works for so many professions. Want to make a product for lawyers? Go to law school and be a lawyer for 10 years. Bam. Next question.
This response is kind of funny but it actually really highlights the wrong way to think about these things as well. The suggestion isn't to have a career in medicine it is to get your boots on the ground. You have to find a clever way to get a vast amount of hands on experience quickly. For lawyers the equivalent won't be going to law school it might be doing transcription or office tasks or secure courier work or being an EA or volunteering at the DA office or some other clever hack.
People are notoriously bad at describing their actual problems. Most of the time, they will describe their perceived solutions. What's worse, even of you get to the bottom of their problem, they won't describe their procedures that they follow day by day. This is because to them it's trivial, on the level of muscle memory, but to you as an outsider it won't even occur to ask about it unless you actually see what they are doing. By just talking to people, no matter how many hours, you'll be missing a lot of context and your product will be bad.
