For something like that, I would contact your VAR so they can troubleshoot the problem - client log files might help. You're though, it should only do the delta from the previous day's changes assuming it finished updating the first time.
I would suggest you think about checking out all of the files that you think you'll want to work on, Get Latest on those that you'll need as references and then use the Tools > Work-Off line mode while you're away. Doing a update local cache on the entire vault is not something I would ever advise, unless you had a very small vault.
I agree with Steve, above we did have our EPDM vault at one time doing update local cache to a library folder that had 10,000 files and that would tie up EPDM for 15-20 mins. each morning on every client. I put an end to once I checked out why in our server settings. Like Steve said above example....when you see in the library files in your assembly that need to be seeing the latest you just right click on the file in the EPDM feature manager tree on the right hand side and do that.
Hope that helps