What is the practical limit to using Dropbox to share a single file?
My experience sharing a spreadsheet that I use to track inventory, is that one person using two computers can use it effectively, but adding a second person or a third computer will not work well.
File Lock Problem
If you add a second person, there’s a huge risk that both will have the document open at the same time, and write into it at the same time.
Too Many Conflicts Problem
If you have three computers, and one computer falls behind many days, the sync might not work. At the very least, you could lose changes from one computer’s edits.
Sometimes, one of the computers will initiate a full sync, and that could take a long time.
Too Many Temporary Files
A system shutdown leaves behind temporary files. The application might see these files, and determine that a recovery should be performed.
File sync copies files, so the temporary files are also copied. The recovery could cause changes to be lost.
This could happen with two computers, but adding a third one just makes it more likely.
The way to fix this is to close the file, while leaving the computer on. This way, files are synced, and temporary files are removed, before you or someone else starts up on another computer.