if this is only about seatime then nobody at the USCG cares one bit. Seatime is used to determine overall experience at a certain grade or level and never was intended to mean exactly so many days of underway watchkeeping, working cargo, performing maintenance, etc… There is no specific standard for any of these job functions.
just look at how the Coast Guard has granted seatime to drilling DPOs who literally are never ever underway except to move from one drillsite to another. In a dozen years they make only have a dozen days of underway but still advance their licenses just the same as a mate always underway. One reason that the USCG should have trade restrictions on licenses especially for drilling mates and masters.