I think you're thinking of how they filmed PIC S2 and S3 back-to-back, not SNW S1 and 2.
That is absolutely not a valid justification for overworking people to the point of endangering their health, which the old system did. Neither is "we pay you" a valid justification for any employer to exploit their workers. "You can just find another job" is the age-old excuse for employers abusing employees, and it's bullshit -- especially in a mercurial industry where an actor's ability to find another job is in fact always precarious and unreliable. It's just another variation of "obey or risk starvation."
Doctor Who has averaged 13 episodes a season pre-covid, and the actors have said the filming schedule was always grueling. You have 2-3 principal cast, who pretty much appear in
every episode, virtually every episode is filmed on location, and the pressure to succeed often induces burnout.
Star Trek is relatively tame, especially on an ensemble show like DSC or ensemble-light like SNW, where 50-75% of the show is filmed on standing sets.
I'm sure a bigger issue is filming in Canada, where I imagine most of the credited cast do not have as their primary residence - they have to spend months at a time away from home and their families, or relocate their families to Toronto.
Still, since a full day of shooting can be upwards of 10 hours, add time for makeup and prosthetics for the alien cast, and even worse days for the studio crew - lighting, sets, electric, sound etc. maybe 10-13 episodes is better after all.
