If it's a busy intersection, chances are you're only allowed to cross when the cars get switched to go in parallel to you.

If it's a normal street, but still with a high volume of pedestrians, then there's likely a sensor to detect waiting pedestrians. Also depends on how new the traffic light installation is and how much the municipality spends on this.
I think, the sensor also allows detecting the number of pedestrians waiting, so they can speed it up.

If it's a street where pedestrians only cross sporadically or an old installation, then the button is likely to work and that you have to press it to ever be allowed to cross. Running a sensor all day just isn't worth it.

Obviously, the specifics depend on the region, but I feel like these are rules of thumb that make sense pretty much everywhere...