Ours is 1 1/4 miles, about half of which is a steep hill (upwards on way to school). It would be shorter along the busy road, but we prefer the longer, mostly traffic free route.
When DS was in reception and DD a baby, we usually 'walked', that is, DS had the scooter for the flat bits, and on the steep bits I'd pull him by a scooter strap (whilst carrying DD in a sling, or pushing the buggy up the hill with my other hand - I was really fit by the end of that year!) That way we were quite fast, maybe 25 minutes compared to 20 minutes when on my own. When DS actually walked, it would be more like 35-40 minutes. For the way home, although downhill, it would rarely take us less than 45 minutes, usually around an hour. It was lovely actually, lots of time to decompress from school, be outside in the fresh air, chatting about everything and anything. Though it did make for short 'evenings'
From Y1 we cycled, again most days, and though initially we weren't faster than me power-walking and pulling DS along on his scooter, after two years we can now do it in 15 minutes, if we're lucky at the traffic lights (the lights regularly add 5 minutes to our trip). By myself I can do it in 10 minutes. But cycling is much less conducive to conversations and a lot more stressful, because you have to be super-alert 100% of the time. It does give us more flexibility and extra time at home though.