You should always use the handbrake but I am not going to lie and pretend I always do, because I don't.
Worse, I often don't use the footbrake either and just use clutch control to hold steady.
That said, I use the handbrake at a pedestrian crossing specifically because of the desire not to be pushed forward and hit them. I'd also use it at a railway crossing and also kill the engine too, although that's to save fuel when I know I'll be stopped a while.
Although my parents were told they escaped serious damage or injury in a recent crash where they were rear ended because my dad hadn't applied the handbrake. My dad spotted the car coming behind him wasn't slowing quick enough so dad released the foot brake and the crash force was much less as his car rolled with the force rather than tried to resist it.I'd never use clutch control to hold steady as that will screw the clutch, but hold foot brake unless on a uphill start.