I hope there are not many people hitting this table. This may be OK as long as it is a nightly run that you know you are the only code running against it.  

However long it runs, it will be locked during this process.  Although fast, for databases with a lot of people expecting to update it, it would be unacceptable unless you can get it to run in less than 4 seconds (you last said 26 seconds I believe) and lock timeout's are set well above that.  Speed is not always the only consideration unless you are running exclusively!  In which case I would put a table lock hint on it to speed it up even more.  I would recommend taking a little longer time to make sure you don't have a table lock for a half minute. 

Mark