I childmind for my daughter and take my grandchildren to and from school 50% of the time.
The children are DGD in year 4, DGS in reception, DGS in nursery.
The youngest, in the school nursery, finishes at 3pm. The nursery children are always stood ready with coats and bags and leave promptly. The rest of the school leave officially at 3.20 but are always later in coming out.
It's a half an hour wait.
Is this common practice? How long do others have to wait to collect children from primary school? My daughter got drenched today and it wasn't raining that fast. (Waterproof coats and a large umbrella, plus 15 min walk home.) She left the house to go to school at 2.45 and got back at 3.45 - an hour in the rain.
I would say that last year it rained more often on my drop offs and pick ups. 
At the school I worked in, there was no more than a 5 min staggered leaving time between the youngest and oldest children leaving.
Is this waiting time common - or is it just this place?