Originally Posted by
fly747first
I have a DL flight in 5 days and the system doesn't give me an option to pay for seats now in BE and in my past experience it was closer to 72 hrs.
Not saying you're wrong

it may not be consistent or universal from one trip to another -- all I can say is that I have two emails saved from two different flights in 2020 that were sent at T-5d. But I have others where I didn't get such an email... /shrug.
Maybe it's like FCM offers where they come and go depending how many seats are left etc.? Although it's kinda funny/demented to think of main cabin seat assignments that way.