That actually can vary as I have mentioned. The flow diagram at the end was for a specific project where I was already given the results of the user research which was done by my client side and my job was to just analyze those and represent them in visually.
But, yes. If you are really going to run a user research and map those needs to a persona it might need more time than that. I think this is a good example for how we need to adjust our processes accordingly.

Appreciate the fact that you raised it. :)