This is not an either/or situation. You are trying to find the right balance. In my view, someone can put so much time and "quality" into one video that a channel will have so few videos because time is a limiting factor. I tend to view "quality" as subjective and you grade it as "A", "B", "C", etc.
Some people always want to score an "A". But if you remember in school, 90% was also an "A" (excellent). Hence, you don't need "perfection" to put out A-quality videos.
If you want to be put a "B" quality video. In school, a "B" was 80%-89% (very good), so you have some play there.
I think that many people will agree that audio quality is very important when it comes to music. If the audio is great, people will forgive some of the visual elements. I play music that SOUNDS GOOD regardless of what happens onscreen. If the audio music SOUNDS very good, I would even take a blank screen if I had to.
I tend to think that people who tend to live in the 95%-100% quality will have a tough time growing their channel. OF COURSE, on Youtube there are always exceptions that can be found. Having said that, there are people who do quite well by posting 1 video per week.