Keepers to total number of shots...

[HannahRebekah]

The lightning shots, I can see. If there's no bolt, it's an obvious throw. But even with birds, unless it's obviously not something that's worth anything, I couldn't see myself parting with anything, lol.

I used to be like that until I realized how much space I was taking up and my computer was bogging down. Now I mostly delete what I have a better shot of. Saves space on both my camera and my computer. And I'm going to guess my ratio is about eh 5ish to 1 on a good day.

 

[Big Mike]

It really depends on what & how you are shooting.

When shooting sports or wildlife, you might shoot fast & furious. You probably can't pose the subject so you are just hoping for that one perfect shot when everything comes together. Keeper rate: very low.

With Landscape photography, on the other hand, you can usually take you time and get everything set up just right. You may only need one shot. But of course, you may want to bracket your exposures, try slightly different compositions and shoot more as the light changes...but still, you're probably not shooting as fast or as often as with wildlife, so the keeper rate is higher.

When shooting events & weddings, the keeper rate depends on exactly what you are shooting. For example, the 'first kiss' is only a couple seconds long, so you might only get a couple shots of it. One of them HAS TO BE a keeper. But most of the rest of the ceremony might look the same (B&G standing at the front of the church). So while you make take 100 shots of it, they all look similar or portray the same thing in a still image.
For the formal & family portraits, it's usually a good idea to get multiple shots of each pose/group, just in case there are closed eyes etc...but for the most part, two or three of each pose is all you'll need.
Then for the reception (or a party type event) each shot might include different people doing different things. You can shoot a lot of photos and they might all be a little different....so they might all be keepers, depending on your use for them. They won't all be exciting but may be of value to the B&G.

For portrait photography, some people shoot a lot, hoping for some good ones (spray & pray). Some photographers, on the other hand, only need a couple or maybe just one frame.
There is certainly nothing wrong with trying many different options, but you really don't want to just shoot and hope (pray) that something good turns out.
I remember reading this many years ago and it's a perfect example for this discussion...

Below are two photos by world-famous portrait photographer: Elsa Dorfman. Elsa has the same kind of studio, background, lights, and equipment as a lot of folks with more technical skill. Yet those folks aren't portrait photographers and Elsa is. What's the difference? Elsa cares about people. She is genuinely curious about people she has never met and can connect with them in just a few minutes. After a one-hour session, she knows more about her average subject's life than I do about my sister's.

Elsa uses a 20x24" Polaroid camera. Film costs about $50/exposure, so she limits herself to two exposures per subject. Yet her photo of me and Alex (below right) is one of the only pictures of myself that I like. Our advice to digital photographers is to fill the flash card with at least 50 images in hopes of yielding one that captures the essence of a subject's expression.

Elsa's artistic success implies that the most important thing about portrait photography is an interest in your subject. If you are so busy working that you can't care about strangers, don't take their photos! Or at rate, don't expect those photos to be good. Some of my better portraits were taken on a trip to Alaska and back because I had 3.5 months in which to be alone and learn to appreciate the value of a stranger's company and conversation.

from HERE

Kids & babies are more like wildlife, so they may need a few more shots that someone who can hold a pose

For anyone who is (or always has been) using digital, I suggest using a film camera for a while. It can really make you think a lot more before you click the shutter, which is always a good thing.