This is one of the many unproductive lines of thinking that inspires me to disregard “terrorism” as an unhelpful concept. Terror is a state of mind/being, not the act of being attacked, or being opposed by an ideology. As an umbrella term, I think it does assume and ask for reactionary behavior.
There are real strategic disadvantages which can occur when hiding or fleeing an assault. Hiding can cause one to be cornered if discovered. Running usually leaves one’s back exposed and temporarily offers an easier target. Calling for help can alert attackers to your location. On an airplane, a drive to avoid individual fatalities can cause the death of the whole group.
The more practical answer I think is usually “it depends”, and try to do a quick risk assessment. Feeling terrified is not conducive to this process! Try to expect possible dangerous situations wherever you may be, but without worrying about them.
