Ah, perhaps in the other corners of the world, but in Finland we do not play such "games". That is, if you invite someone over by 17 pm, it might mean by 18 pm, or might not. Here, if you invite someone at 17 pm, whatever the cause, that is the target one should be aiming for. Some think of our culture as too direct or blunt, but in my mind ambiguity and misunderstandings are a root cause of much misery. :)

You routinely have 45 minute swings in amounts of traffic, and you can’t know in advance what the traffic is going to be like? That seems insane to me. Sure every now and agai there’s an accident or road works, but for it to often take 30 minutes longer, or 15 minutes less seems bizzare to me. Or is it a case of you can leave and be there 15 minutes early, or you can wait 30 mins and be 30 mins late due to traffic? In that case, you’re making he decision that you’d rather be late.