For a year I have shot almost everything on a single 35mm lens. Portraits, landscapes, street, food. When the frame is wrong I move my feet instead of twisting a ring.
The constraint sounds limiting. In practice it removed a decision from every picture and gave that energy back to composition.
Seeing in one frame
After a few months you start to see in thirty-five millimetres. You know before raising the camera where the edges will fall. That intuition is worth more than any zoom range.
If you own five lenses, try leaving four at home for a month. You might not want them back.