The traffic that's not doing the school run is doing other things instead - like heading for the coast at the slightest hint of sunshine.
My route to work unfortunately involves crossing or using the A64 - the main route to Scarborough, Whitby, Filey, Bridlington... During the summer, the traffic's brought down to around 15 or 20mph for stretches, which might seem like a good thing, but...
at junctions, where you want to join or cross, actually crossing two stream of nose-to-tail crawling traffic is very difficult. Folk waiting to join or cross get impatient, jump the queue or try to force their way in and sooner or later, there'll be a crunch.
About this time two years ago, I was one of those crunched. Very cautious now!