But I don't need to know the time when I'm going somewhere. I need to know the time before I set off, so I set off at the right time, and then I get there at the right time.
It's quite simple really.
If I want to be somewhere 250 miles away, I know it takes about six hours to drive there. So, in order to get there in time, I leave maybe six and a half hours before I need to be there. If I know the road is going to be busy - quite often where I live there are a lot of tourists doing 30mph with no idea there's anyone else on the road - I'll give it even more time.
Dead easy.