There's obviously a disconnect between people's experiences here and Adobe generally stating that offline mode 'should work'. People are saying that offline mode is not working on their computers and Adobe needs to address this problem. I am asked to sign in everytime I open the Premiere and have no option to work in offline mode or a warning saying I need to sign in within 30/90 days. I'm working in windows 10, a maingear vector pro laptop. The only thread that seems useful is the one mentioning the "wonky BIOS setting of AGESA Combo Pi v2 220.127.116.11" but it seems odd we would have to revert BIOS to deal with this problem.
That does have more limits. The yearly subscribers can go 90 days between connections to the CC Cloud, but monthly have a much smaller time frame. I don't know exactly what it is, that would need to be checked with their staff.
In offline mode, annual Creative Cloud members get 99 days of grace period; month-to-month members get 30 days of grace period. Note that the grace period may vary according to your subscription status, type of commitment, billing status, and how you purchased your software (directly from Adobe or via a third-party retailer).