When I was first traveling by bus, a friend told me to always check to make sure I was getting on the right bus as sometimes a bus will change or be moved to a different loading location. Most of the time, they announce the change over the speakers, but it can be easily missed if the terminal is noisy enough.
I carried this knowledge with me on the few trains I have ridden later. I also remembered this when I travel by plane. It came in handy about 19 or 20 years ago. I was traveling to Portland, Maine by way of Chicago, Illinois. When I landed in Chicago, I went to the monitors to verify which gate I needed to board. When I arrived at the gate, the sign showed Portland, Maine. I had about 2 hours before boarding, but about every 30 minutes, it still showed Portland. On my last check 30 minutes before boarding, I looked up and saw New Hampshire was now showing. I didn’t hear them announce a gate change for my plane. I went to the nearest set of schedule monitors and found my flight had been switched to a gate a long distance from where I was at. I don’t run, but I fast-walked to the new gate, arriving a few minutes before boarding began.