The optimizer works against SELECT statements.
The optimizer does not affect how a table is Updated.
When you ask SQL-Server to updated Every row, then it will Update EVERY Row.
It will also take a lot longer to do this because you're affecting every row; which I believe means it will affect your transaction log too.
Be VERY Careful NOT do this.
You will create Exclusive Locks on EVERY Record in the entire table when this happens.
Even if the data is not actually changing, SQL-Server will still update the record nonetheless.
This Might Cause Deadlocks on that table if another process tries to use it during that time.
I speak from experience where every night our main database table would lock up for 15 minutes while a process (someone else wrote) was updating the entire table... Twice.
This caused all the other queries to wait for it to complete (some would timeout).
Not even a simple Select statement could be run against it while it was Updating.