It depends on:
1. Is it legal? Check with state and local game laws. Here in Colorado 35 lbs. is legal minimum for a hunting bow.
2. Is the bow properly tuned and will it be shot with matched arrows and well sharpened, properly mounted broadheads? As simple as a stickbow is, it still needs to be tuned. Arrows need to be matched to the bow and the shooter's style. Broadhead selection is critical. Go to a good pro shop that specializes in traditional gear. Modern recurves are very efficient. Make sure she has a good bow.
3. Is your friend in good shape? Is she getting everything she can out of her bow? Draw weight is measured at 28 inches. Deduct (or add) 5 lbs per inch of variance. For example, I shoot a 40 pound bow (it actually scales at 43 pounds) but I draw 29 1/4 inches so I am shooting closer to 50 pounds. I practiced a lot to get a good draw. I have shot with guys pulling bows over 70 pounds. I notice that they do not pull to a full draw. They release at about a 3/4 draw and then keep their hands moving back to the ear, thinking that they are still drawing. My arrows go just as deep into the 3D targets as theirs do.
4. Does your friend know deer anatomy? When a broadhead severs a major artery, the deer does not know (or care) whether it was shot from a 40# bow or a 90# bow. The deer is dead. Shot placement is everything.
There is a growing consensus among trad. archers that it is more important to shoot a weight that you are comfortable with and can get accurate shot placement with well tuned gear than it is to pull a heavy bow. Maybe it is because we are all getting older. I like to think that it is because we are getting smarter.
Go to
www.stickbow.com and click on the leatherwall forum. This question is asked there all the time. The search engine should work for guests or just register, it is free. Lots of posts indicate that you can get a pass-through with a 40 pound bow. In the golden age of traditional archery (1960's) 40 pounds was fairly standard for a hunting bow.
Shoot safe and good hunting.