There can be much confusion over the words sheet ~ leaf ~ page. To check on all this I looked up some of the top ten entries ~ out of more than five billion ~ for page in the Google search engine. Here are some of the results ~ I do not quote source because the WWW notoriously quotes ~ or misquotes ~ original sources without acknowledging them.
The last of these appeals to me most of all. The author quoted has chosen to refer to pieces of paper. I would prefer leaf or leaves ~ but accept that many people are unfamiliar with that word in the context of book. I am not happy about sheet since ~ to a printer of books especially ~ it could mean 32 pages of a book before collation.
There are two reasons why I am keen to chatter about this subject. The second is the more important ~ the first is a bit pompous and philosopical. Please bear with me ~ it may be of use to some folk. After sixty years as a teacher I never recall having been given the advice ~ not in training college ~ or since ~ that successful teaching ~ and even communication in general ~ depends not just on knowing what you are talking ~ or writing about ~ about. It depends on how you say ~ or write ~ it. It then depends on what the recipient hears ~ or reads. (As I sat in the second row of a huge lecture hall I recall ~ at the start of a lecture ~ one member of the 'Education Staff' feebly asking 'Can you hear me at the back?' Only the lip readers with keen eyesight would have been able to respond.) All the foregoing factors come to nought if the listener ~ or reader ~ fails to understand the message. Even then all is lost unless the message is heeded
Understanding the word page often it does not matter and is easily clarified by the careful prepartion of the context. Be aware that there can easily be a misunderstanding on WWW-sales sites. I have often read comments such as 'I expected 80 pages...there were only 40'. The sales-blurb should ~ presumably ~ have read '40 sides' instead of '40 pages' or better still ~ '40 sides on 20 leaves'.
Advertising a book as having of '80 pages' upsets a buyer who expects a page to be two sides of paper. It may sound odd ~ but I have seen numerous complaints in the comments columns from people who expect ~ or hope for ~ twice as much as they will receive. To avoid accusations of dishonesty, listings have to be carefully compiled.
I try to use a phrase such as 'pages ~ as if numbered in a book', or else spell out my understanding of the various words. Maybe I make it even more complicated by introducing the words folio and section. They are explained elsewhere .