There is always a closing date set, which is typically 30 -45 days. In many cases it is almost impossible to get the paperwork done, the appraisal completed and the closing set within this time limit when interest rates drop. There is small fee, usually about one quarter of a percentage that will allow this time to extend without a penalty cost or the refinance falling through.
Refinancing will prove to be fruitful for you when all of the closing rates are included in the rate and there are no cost rates available. In such cases only a little reduction of the rate will be required.