One creative idea for your documentation – SSARS 19 has a helpful comment that the documentation for a review can rely on documents outside of that particular engagement.
The specific examples mentioned in SSARS 19 are other engagement files, quality control files, or consultation services. This means documentation for your current review could be in another review or comp file or in a file of consultation discussions or projects.
Let’s say you are providing monthly or quarterly compilations to a client and then perform a review at the end of the year. If there is a calculation you have to review for every compilation, then you probably have one worksheet that you roll forward every time you provide a compilation. When you get to the annual review, you could roll that other workpaper forward again and use that workpaper as a part of the review. The workpaper in the monthly comp file would be acceptable as documentation for the review. You do not have to duplicate that workpaper in the review file.
It would probably be a really good idea to include a cross-reference to the other workpaper in your current review. If you rolled that workpaper forward to the review in following years, you should keep in mind the timeline for document retention.