Not sure which state you are interested in but this is from the Texas RRC site FAQ about the life of permits which I did not realize but went searching for the answer after seeing this thread.
“You are allowed two years from the date of approval of first filing to spud the well. If you have not spud the well and are amending the filing with 30 days or less before the permit expires, the system will inform you that you only have 30 days to spud your well or it will expire and any amendments will not matter. ANY AMENDMENTS THAT ARE MADE TO FILING AFTER THE INITIAL APPROVAL DATE DOES NOT PROLONG THE LIFE OF THE PERMIT.”