The amount of work that vfx studios do in such a short time is staggering. I have some friends in the industry and I'm always worried about how the unhinged demands of their profession keep them away from their families. Many studios are set up in such a way that makes it impossible for staff to unionize and fight for better working conditions.
With that in mind, I don't give a rats ass if I see a Disco ship for 8 seconds. I know nothing of the time pressures involved in this particular shot, but I wouldn't be surprised if, for example, it was done as fast as possible, late at night, because vfx for another show needed to be started the next day.
This is nothing new either: During the production of Enterprise season 3, the staff had a matter of days to come up with a design and cg model an Enterprise J. Now, I know more about scifi starships than I care to admit, and am also decent cg modeller, but if someone came up to me and said 'Build an Enterprise in two days.', I would struggle. That episode also reused a 24th century Nova class and the fake Starfleet ship Dauntless in a scene depicting the 26th century. Were the vfx guys lazy? No. They were rushed off their feet.