Why use a nested system? Because this allows you to have a very short list to choose from at any given time and prevents having to scroll down, while seeking a specific word, a long list of keywords. A nested system also allows you to quickly, within seconds, find a specific subject image, such as birds, or a family member. This also saves time. I like to work quick and easy so I try to stay organized. Keywords are also very easy to alter by choosing the keyword and then using the right click, so you fix errors quickly and easily. I do not keyword upon import unless every single image is the same subject, then I would keyword at import. I generally keyword at some point after I've imported the images and played with them to process (I shoot RAW). There are many ways to keyword, I think I counted seven in all but there could be more. I cannot include text from the Nikonian article that I wrote as they now own it or I would. If you have been key wording and want to find the images that do not contain a keyword you can do that in the included Smart Collection that is standard in LrC. It's easy to keyword, for me, in the morning with a cup of coffee in hand and it goes very quickly. Your keyword list must match what you shoot in general and should be designed to grow as needed. Again, doing this on paper first is the best approach. Keywording can save countless minutes/hours of time when you are working on a special project or looking for images for a competition or to sell. I've included a few screenshots to clarify.

Why use a nested system? Because this allows you to have a very short list to choose from at any given time and prevents having to scroll down, while seeking a specific word, a long list of keywords. A nested system also allows you to quickly, within seconds, find a specific subject image, such as birds, or a family member. This also saves time. I like to work quick and easy so I try to stay organized. Keywords are also very easy to alter by choosing the keyword and then using the right click, so you fix errors quickly and easily. I do not keyword upon import unless every single image is the same subject, then I would keyword at import. I generally keyword at some point after I've imported the images and played with them to process (I shoot RAW). There are many ways to keyword, I think I counted seven in all but there could be more. I cannot include text from the Nikonian article that I wrote as they now own it or I would. If you have been key wording and want to find the images that do not contain a keyword you can do that in the included Smart Collection that is standard in LrC. It's easy to keyword, for me, in the morning with a cup of coffee in hand and it goes very quickly. Your keyword list must match what you shoot in general and should be designed to grow as needed. Again, doing this on paper first is the best approach. Keywording can save countless minutes/hours of time when you are working on a special project or looking for images for a competition or to sell. I've included a few screenshots to clarify.

I should also note that I have been using keywords since my early days with LR. I find them VERY useful, in fact they are my primary mode of searching for images.

Yes, it takes some time to apply keywords but there are some ways to speed up the process.

When importing a group of images you can apply keywords to all of them in the import dialog. I apply the keywords that are applicable to all of them. If there are only 2 or 3 images in a large group that are not appropriate to a keyword I will probably apply those keywords anyway. I can delete them from the inappropriate images later.

After culling, I select the keepers and go through them to add appropriate keywords if needed. The generic keywords are already there so not all the images need more keywords added. However, I try to add the names of everyone in the image (unless it's a really large group). That is frequently the most time consuming step. However, as I age, I have had several occasions to come up with images of a specific individual for a memorial service. Having the names in the keywords makes the search happen in seconds rather than hours. Time invested now will reduce time spent later.

When you have several images that need the same keyword added, you can select them all in Library Grid mode and add the keyword and it appears on all the images. (There's some possibility that a Mac will do this outside of Library Grid Mode but not having a Mac I can't check that). There is also a "spray can" which you can use to select keywords and spray them onto selected images individually.

Who, what, where, when (maybe why).

I only have about 5,000 photos to manage.

I use all the tools for data base management that LR Classic provides. When I download from camera, LR creates a file on my system drive by download date. When I get over the lazyies (not a real word) I cull, key word, adjust white balance and and assign to a Collection. Following Scott Kelby's sage advice I NEVER work in the Catalog File. Key words are added as Birds>Mockingbirds and Thrashers>Curve-billed Thrasher, if I take the file to Topaz Studio 2 I may add something like >Abstract to the key word list.

Probably not a reasonable procedure for everyone but it works for me.

That may be, but as I stated, each person must determine what keywording system works for them and the way their brain thinks. Also, images can have multiple keywords as determined by the user. For example, I could put a keyword on an image for both nature and landscape and that way I don't miss an image. In my mind for my key wording system "nature" means that intimate close up shot and "landscape" means that wider, more inclusive shot and that works well for me, but maybe not for you. You would need to determine what works for you personally. While you may not feel inclined to use a keyword system thousands of people do this and find it useful. I'm not sure why you are reading this particular thread if you don't want to learn more about key wording. I've found it incredibly useful and a great time saver to find images for all kinds of reasons. Good luck with your image organization.