Good times to hitchhike
Sunday morning until noon seems the worst time to hitchhike in Europe, and many other parts of the "developed" world influenced by Christianity (the US, Oz, Kiwiland and Canadialand come to mind). Cars are full of families, with a grumpy wife on the side and not too many working people on the road. It usually gets better in the afternoon, when people are driving back from their weekend trip alone.
In Israel people work on Sundays so you'll be fine, but Shabbath is a horrible day for hitchhiking there since religious people are not driving at all (and they're usually quite skilled at picking up hitchhikers).
In a lot of european countries, most of the trucks are not allowed on the highways all Sunday. They too are a hitchhiker-fond crowd. Sometimes.