It is not exactly transferable to learning to fly, but there is an interesting story in the paper of a new studyat John's Hopkins University.
It says, that when learning to do a new skill, there needs to be a time, up to 6 hours, for the brain to process what has been learned.
And if something new interferes in the meantime, then the first thing learned is not as imprinted in the brain.

I know that when learning, I wanted to really get the fundementals solid before moving on. This is really true of instrument flight where you have to control the planes attitude before it is really possible to track an instrument well.