Agreed, on the last 5+ Princess cruises, no-one at check-in has ever looked at or mentioned our boarding time. With flights, luggage and Uber transfer (from Miami or Fort Lauderdale airports), I can’t time it properly anyway. So I usually pick an early time for us, and no-one cared if we showed up even before our slot. I may mention that we are Elite, so we skipped a couple of lines here and there.