It all comes down to the needs of the plot always had done, and no doubt always will.
Someone cited VOY at Warp 9.9 was ~21 500c which mean the trip home would take 3.5 or so years and not the 70 so often stated.
But it wasn't plot conveniant. So it was ignored. A part of any TV audiance doesn't care about such things, whilst others do. If we take another franchise with multiple spin-offs say the L&0 universe, do we as an audiance expect conistancy between the various shows, such as who is DA? or that if one show says the death penatly can't ber saought do we expect that to apply in all shows unless they state in dialouge that the policy has changed?