Most sites I know do not fill in their image alt text for many images. I know a lot of SEOs work on this task but sometimes it is a lot of work. One SEO said his client wants to take a shortcut and autofill any blank alt text with his company name. John Mueller from Google responded to that saying "it makes no sense" to do that.
John added not only does it make no sense, it would be a waste of time to do that.
The alt text for an image, by definition, is suppose to explain what the image is - it should describe the image for those who cannot see the image. If you just put in your company name, it does not describe the image, unless that is your company logo - I guess. I mean, on Google.com, the Google logo's alt text is "Google" and not "Google logo." But if you have a photo of someone and instead of saying in the alt text "Photo of name goes here" and you put in your company name - that is not helpful to you, your users, and to search engines.
And if you are trying to save time by doing this, all you are doing is wasting time, John added.
Here are those tweets:
It makes no sense, it seems like a waste of time to me: once wasted time to implement, and again wasted time to clean up later on.
— 🐝 johnmu.xml (personal) 🐝 (@JohnMu) June 2, 2022
Forum discussion at Twitter.