Apparently it's to do with a 'recovery period'.
I don't agree with it and don't understand it, to be honest.
Looking at our fixtures as well, we've got quite a few gaps in our fixtures even with the late start. The biggest gap being 6 days between playing Pakistan on 16th and Afghanistan on 22nd. Then 5 days after that to play West Indies.
Shortest gap is England on 30th June then Bangladesh on 2nd July.