WSUS downloading driver updates every night
Enought free space on the partition where updates are downloaded ?
IMHO it's a nonsense to download all from WSUS.
Why you don't mark the checkbox "Download update files to this server only when updates are approved" in Options / Update Files and Languages.
You will receive the information about the update and after the approve it will be downloaded. Obviously you should only approve the updates some of your computers in your network needs. You can see if some of your computers need that update adding the column "required count" on the pane with the updates.