From my experience (3 years)
1. like others say, it does take a lot of your time. 20 hours may not sound like a lot, but there are also other commitments like having data in a
perfect graph for publication, and often your PI ( principle investigator) will want you to do poster presentations (far from your experience in high school) and contribute to the lab. Plus, you are responsible for knowing what other research is being performed in the area you will be working in. When I started research as a freshman, it took me 4 text books, Google, and about 3 hours to finish one page of a manuscript (published data written at the professional level).
2. There are a lot of benefits though. You learn advanced techniques, learn how to read manuscripts, learn calculations for courses like analytical chem, become more familiar with the expectations of the field. Presenting your research is very time consuming but extremely beneficial. Through my research I traveled about three times a year to present my research. Depending on the level of conference, I did everything from poster presentation to a power point lecture. The best part is that I got to travel for free and speak with other students professors about their research.
3. My school offers either credit hours or payment through the PI's grant money. This is semester based and one semester of 20 hours per week was worth 1 credit hour.
4. As far a being a lab rat to produce one small amount of data for a manuscript for your PI. . . . Yep that is what it is about.
But if you are truly interested, and you produce good work, then you get better assignments. I worked in a lab for about 2 years and transferred schools (married). I quickly researched a lab and the publications from their lab. (more quality publications= better lab). Once I was accepted into a lab, I was given an introductory project that was supposed to take one or two weeks. It took one year and a half because we kept finding information to pursue. I also was primary author on the manuscript
😀.
5. Keep in mind, some PharmD. schools love research, some do not.
6. If you are incredibly on top of it, determined, and focused, you can do research and coursework. I did research 20+hrs/week, worked 30 hrs/week, was a Teaching assistant~8hrs/week, had organic chem, calculus, and Physics in the same semester. I DO NOT ADVISE THIS! I got behind in organic and never caught up. Probably could have made it if I wasn't supporting my parents. (dad lost job had to pick up some more hours to help them with their bills)
Sorry for a long reply, if you can afford to not work while in school, go for it. But make sure you are picking a professor that Cares about your success, not just the labs success. You can tell this from other students currently working in a lab. If you want to find them, they will be in their lab

, just go to the lab, someone will be there.