This is an almost opposite to this problem - My workmate keeps an Excel spreadsheet open for a whole day (she has good reasons to do so) without editing. Now if someone else would like to access this file, the "file is open by another user..." warning should appear, but I've noticed that if the file was left open for a long period of time without any changes made to it, this warning won't show up. This leads to potential issues with the same file being edited at the same time.
Is there a way to change this timout?