It really depends. An overall shoddy show can't be saved by jumbling up it's premise. Look at
Columbo or Star Treck: Every episode the same, but still good writing/acting that makes the most of it.
There are some shows where I can easily overlook it. Southpark, the Simpsons, Futurama; They all have tons of repetitive parts in them, that just get reheated for the occasion.
However I like shows most for their original parts. It doesn't have to be the mighty boosh, but just because you can label shows like The Killing as a murder mystery and know 90% of the plot, doesn't mean that it isn't one of the top five shows I have ever watched by my judgement.