I'll throw my own twist on the conversation...

How and where you will hunt will also effect what barrel length and choke combo you choose. If you're hunting in pretty dense marshland edges with good cover and high populations, your average shot may be 20yrds on low flying birds. If you're hunting open ground, or over prairie ponds, trying to catch fast and high flyers, it might demand much longer shots. Obviously, the shot, barrel length, and choke you use to take down a "settling" dove at 20yrds will be different than what you need to knock down a high flyer at 40-50yrds.

Personally, I prefer to have dense shot patterns so I can reach out farther. For me, yes, it makes the close shots a little harder, since the spread is smaller, but the target is closer, so it's also easier to hit and appears "bigger", and then my pattern will still be dense enough at longer ranges to put shot to feather. Even if I miss a close range shot (doesn't happen much, but let's just say...), the dove will be flying AWAY, so if it's too dense up close, the spread will let me pick them up on the way out. So my method is to shoot a lower number shot with a tighter choke, and longer barrel. I usually hunt with 6's or 7.5's, a 12ga 3" and 26" barrel and mod choke. I also tend to hunt over prairie ponds without good cover, and the dove don't typically get very close.

At the other end of the spectrum, some shooters prefer to have a wider spread, to make the close shots easy. My problem with this method is that the lighter shot doesn't hold energy as well, and the wide shot patterns mean your range is significantly shortened. Shooting 9's from a cylinder bore and a 22" barrel might make those shots "right at the end of your barrel" easier, but you CANNOT reach down range very far before your group opens up and your shot looses energy.

So you kinda have to choose where on that continuum you want to fall. Hand throw a few clays low, close, and fast across her some time, and see how well she picks them up. If she's getting a lot of misses, swap up shot numbers or chokes to open her pattern and see if that improves her hit percentages. Then see how well that combo performs at longer ranges. If the combo she feels good with at 20yrds works well at 40yrds, then you're set. If the good 20yrd combo isn't breaking clays at 40yrds, then you'll have to find a compromise in between.