There are any number of firsthand RAF/RCAF/RAAF/SAAF/RZNAF accounts that document the relatively lengthy period of pilot training, even during the dark days of the Battle of Britain.
Yes, read Geoffrey Wellum, First Light, for evidence of this. He was trained in 1939/40, before OTUs came into being, and even then had a reasonable amount of training. It was only in WW1 that pilots were sent off with 20 hours to fight the enemy.
David