Great list - I totally agree with the "little and often". I think charity shops get better and better every year - I never cease to be amazed at what's available (and even more amazed by people whose opinion is stuck in the dark ages, and who won't go near charity shops because they think they are stuffed with "old lady clothes").
Disagree on trousers, though. If you work in an office, like me, charity shops are a godsend for classic tailored trousers - the sort that wear and wash well, and stay in fashion. Ditto shirts - they never really date or wear out. My fave pair of white skinny jeans (Mint Velvet) came from BHF.
Teeshirts/jersey/acrylic knits - I agree - very rarely do I find anything in decent condition, so I avoid.
It's worth noting that some charity shops "know" the value of a label, and others don't. Cancer Research and BHF here are stuffed with LK Bennett, Boden, Jaeger, Hobbs etc; Cancer Research price accordingly, but BHF don't seem to. That's where the bargains are.
Lastly, you say pricing depends on the chain....but BHF in our naice MC town tends to price a lot higher than the branch in the large "low-income" town 20 miles away.