Here's how I use mine, hoping it practically helps understanding lenses:
My favorite lens is 28mm f/2.8. The reason is the versatility it has. It is a primer lens, which means it does not allow you to zoom in or out. In that case, the zoom is your legs. It is perfect for photographing documentaries, which can be at weddings, inside family houses, or reduced spaces as a business owner's office. It is the perfect lens to tell stories as you need to be close and make the viewer feel like it is inside the action. Also, this lens allows us to make interesting angles. The bad thing about it is you need to be aware of the edges, as borders might look distorted if not using it correctly.
Then I must mention the 16-28mm, which I bought exclusively for landscapes and architecture pictures. This lens is making the most of my Amsterdam images and is the perfect tool for small indoor spaces. Again, the bad thing would be not being aware of the edges or including more things in a frame that sometimes oversaturate the information described in the image.
Finally, the 85mm f/1.8 allows me to be close but not to close. It gives me separation from my clients and makes the most beautiful portraits. Indeed I tend to use the 28mm for environmental portraits and have a bit of the city included. Still, sometimes, mostly at the beginning of the session, I give clients some space to be comfortable using the 85mm before making the picture that goes to walls with the 28mm. This lens is also perfect for detailed shots and respectful during religious ceremonies, capturing the emotion without being intrusive. The bad thing is the beautiful bokeh can capture you too much and make you overuse it. It is good to have a variety of perspectives while doing images,
The best advice I can give you if you are looking for a new lens is to define its purpose first, then, if possible, rent or borrow it to try it first. If you are already working with wedding/event clients, be aware two cameras are needed to save time and capture the moments in two different moods. You can have the amazing environmental portrait with the city in the back with a 28mm while you are doing a close up with the 85mm in less than 1 second of difference.
If you are curious about my photography or the courses, I give the link to my bio to check out more.