I always found mechanical fear in role-playing games an odd thing, especially because it is often disconnected from actual fear. That emotion the players actually feel and have their characters react accordingly to.
I find (players) and their characters often fear things because they are dangerous, unpredictable, have dire consequences or the GM simply has created an effective spooky atmosphere. They rarely fear something because someone asks them they fail a fear check.
I do not need to ask the players to roll a fear check when some dread dark Jedi appears of which they have heard terrible rumors for some time. The fact alone is enough to make the players scramble and have their faces turn white.
Conversely, when something the players don't actually fear something (because it is not a threat when looking at it from a narrative or game-mechanics) it is really hard to have them act that way.
That is why I find a fear mechanic rather misplaced and ultimately very unsatisfying. The rules sometimes say 'you fear this' while it doesn't make any narrative sense to do so.
If I am a GM, as a consequence, I never have players make fear checks. I find it nonsense. But as a player I have suggested GMs who do use it, to make it an actual choice after failing a fear check: either you give in to the fear, and take the penalty the GM has decided, or you decide to overcome your fear, taking X strain damage (depending on how badly you failed the check) instead. I found this to be a much more interesting use of the mechanic, who gives players more narrative options how to handle mechanical fear.
Actual fear still beats check-induced-fear by a huge margin though.
How do you handle fear checks? And do you find your failed fear checks generate actual fear?