If my largest Label Set contained only four labels like yours, I wouldn't use them as regularly as I do for the reasons you explained. I have only two Label Sets containing so few labels and I use each of them to quickly assign all four labels at once pertaining to images that include my wife and/or me. My next smallest Label Set contains eight labels and I have a couple that contain about 50 labels.
I also imagine that people who assign relatively few labels on average per image have far less use for Label Sets. I assign a relatively large number of labels, as was indicated in a thread that captured that data from several of us who participated.
lippe wrote:I created a Labels set with the family members because they often show up on the images. But then i thought this is not the right use of the label sets when is don't assign them all at once, I have to use the favorites for this.
I actually don't use the Favorites category for reasons explained below pertaining mostly to how my mind works. Instead, I established a Label Set named "1 Common Global Labels." That set contains certain labels that I assign at the beginning of my labeling workflow that are to be considered for every image or almost every image. As an example, I indicate that every image is either horizontal, vertical or square, so those labels are included in that set. The number "1" is included in the name of the Label Set to position it at the top of all Label Sets, which helps me adhere to a consistent workflow, which in turn helps prevent me from making errors of omission. I have another Label Set named "2 Favorites." That set essentially serves the purpose of the built-in Favorites. However, the number "2" positions that label set immediately below the the other set already mentioned, which helps keep my workflow consistent. Relative to all of that, I never use the built-in Favorites, Sugested, or Nearby Labels, so my eye quickly skips past all of them to get to my custom Label Sets.
Is there no shortcut for assign (or revoke when already assigned)
I have no idea. I rarely use keyboard shortcuts so that doesn't matter to me.
The third use as 'reminder', i probably to not understand fully:
I'll explain by example: I specialize in studio photography of glass and wine. When cataloging a photo of wine being poured into a decanter, I assigned 17 catalog labels. I couldn't possibly remember all of the labels I would want to consider without a reminder list. My reminder lists for that photo and others with similar content of wine and glass are the Label Sets "Wine" and "Glass." Relying on the built-in Label Set, "Favorites," wouldn't be effective for me because the labels that apply to wine or glass are favorites only when I'm cataloging that kind of photography, not when I'm cataloging photos taken while hiking in the mountains. Similarly, after cataloging a lot of photos of mountain scenery, the favorites that would apply to photos of wine or glass would no longer be displayed in the built-in "Recently Used" set. Make sense?