DD's school teaches joined up writing right from reception. All phonics are taught with lead-in and lead-out strokes right from week one, with the expectation that they should be joined together.
I think that this approach is confusing for children who may have only recently learned to write (by printing).
I also think it deters them from developing their writing as there is so much for them to do, it makes writing so much more effort.
My dd is pretty bright, but reluctant to write anything of any length as it is 'hard'. Her friends at other schools have much clearer writing and seem happier for it.
Why do some schools have this policy? Do you think it is a good idea?