I have about 100 worksheets, each has an identical structure.
The area on each worksheet to be printed is small. ...
Can I print all worksheets at once and use fewer than 50 double sided
pages?

If you do this sort of thing a lot, "fineprint" might help:
http://www.fineprint.com/products/fineprint/index.html

Among its features is the ability to print four-up; that is, to print four
"pages" on one side of one sheet. Two-up and eight-up, too.

It isn't free, but it's worth the price if you use its features a lot.

(I'm not affiliated with fineprint except as a customer. It has been useful
to me.)