Great question! I’ll start by saying that each school has different requirements, and the best thing you can do is check with the schools to which you’re applying (or interested) to make sure you meet their requirements.
That said, the reason schools require observation hours in the first place is to ensure that you want to be a PT, understand what a PT does and realize how much they know that you must learn. Many schools require applicants to observe or work in inpatient and outpatient settings because the sites can be very different, and it’s helpful to have a basic understanding of both.
In an outpatient setting, patients often see a PT in a private practice or similar site and do not stay overnight. They may see the PT without having previously seen a doctor and are usually dealing with more moderate injuries and conditions. Although the PT may consult with a doctor occasionally, they work mostly independently.
In inpatient settings, such as a hospital, patients stay overnight and typically have more severe injuries or conditions. The PT is part of a team made up of doctors, nurses, social workers, etc., who work together to treat the patient. Inpatient sites include acute settings, which the APTA defines as a site in which “physical therapy is provided to individuals who are admitted to a hospital for short-term patient care for reasons such as illness, surgery, accident, or recovery from a trauma.” Inpatient settings can also include cardiac rehab, for patients with heart conditions, or rehab patients with brain injuries, which I suspect includes the site you mentioned. Since cardiac rehab is just one of many types of inpatient settings, I doubt that many (if any) schools require it as a pre-requisite. I’m sure that the brain injury center you mention will be a great inpatient experience, and it may count as an acute setting, but you’d have to check that with the center.
For a more thorough look at different environments in which PT’s work, check out this APTA website.
I’m very glad I came into school with both inpatient and outpatient experience under my belt because they helped me better understand how I might apply what I’m learning in different classes, and also begin thinking about where I might work someday. While it’s a good idea to gain a variety of experiences, it’s impossible to experience everything. You’ll also be exposed to a host of new settings in school. I hope the brain injury center works out, and please let me know how it goes!