I'm struggling to recall the term for when you clone a clone, or grow bacteria by sampling a good healthy batch but then sampling the sample. Repeat, and soon so many errors accumulate that the last copies in the chain die. It's not "generation loss", but something like that?
Kate Orman
Without watching more than four episodes of Doctor Who I can tell you what the problem is with Doctor Who.
It's a long-running franchise. And in the end every long-running franchise, from Batman to Star Trek to Simpsons, ossifies. It becomes wholly about itself.