1, the design of books, except the content is the cover. Originally, your content was arranged, and the cover was designed and you can sell it. But you can't put it on the shelf without shouting. Without selling points and recommendations, why should others buy your book?
At this time, your publishing house will take this new book to some activities or invite some celebrities to make recommendations. These book pushing activities are relatively quick and flexible temporary decisions, and the variables are often relatively large, and there are often sudden adjustments.
Therefore, it is impossible for us to predict these activities in advance, and it is impossible to determine who to invite in advance at the stage of book printing. Assuming that we have arranged in advance, it is impossible for us to tear off the cover of the book and reprint it when the characters or activities change.
At this time, the waist seal came into being. You can print the content flexibly according to the arrangement of the active characters, and then just bread it outside the book. Even if there are changes, you can urgently reprint the waist seal and replace it. This flexibility can not only save costs, but also ensure the printing and distribution of books.
There is no strict size standard for the waist seal itself. It can be wide or narrow, and even cover the whole cover, just like you said. There is even a full cover with a small waist seal outside.
In a word, this is the product of flexible cooperation with publishing and distribution activities. If you think it is in the way, you can throw it away.