I haven't been fortunate enough to work on a PFI only engine, only PFI+DI, and they only use PFI for 10-20% of the fuel at WOT. That said, except for a few very specific engines and circumstances, the port injectors are spraying ONLY while the intake valve is closed, they're timed to complete injecting just before the intake valve opens. The dual cone pattern is critical to distribute fuel onto the back of both valves equally and keep it off the port walls as much as possible. Fuel on the port wall causes all sorts of tranisent/event-to-event fueling problems. It was counter intuitive to me at first, but two main things are happening:
First, heat from combustion is going into the intake valves which have poor cooling from the small contact patch at the seat of materials that are durable, but that don't conduct heat very well. That heat goes into the fuel, helping vaporize it and simultaneously cooling the valve.
Second, the pressure in the combustion chamber at the end of the exhaust stroke is quite high (relative to the pressure at the intake port), and at/near TDC there is no piston movement to draw in fresh intake air. When the intake valve cracks open, that pressure blows the fuel off the back of the valve and into the intake port, helping to atomize it.
I've got some PFI videos looking at the back of the intake valves somewhere, I'll see if I can't get them uploaded later.
