I would generally say, "ask for forgiveness not permission if you'll be fine walking back your decision later."
Forgiveness often makes sense at work, at least for software engineers, and for modest decisions. Do things the way you think is best instead of getting blocked for weeks looking for permission. If, later on, someone comes knocking and wanting to change it, fine, whatever.
However, taking the "forgiveness" route with more important / harder to change / expensive things - like building some addition to your house, building a software business separate your software job - is a recipe for disaster.
Forgiveness often makes sense at work, at least for software engineers, and for modest decisions. Do things the way you think is best instead of getting blocked for weeks looking for permission. If, later on, someone comes knocking and wanting to change it, fine, whatever.
However, taking the "forgiveness" route with more important / harder to change / expensive things - like building some addition to your house, building a software business separate your software job - is a recipe for disaster.