Sue
"Luna, you mention placing exclusive pairs/multiples, but how do you know what goes where. "
I re-read my post and I'm not sure where you get this from - or what you mean! I do understand about them driving you mad though, I have, literally, taken all weekend to solve a Fiendish one from the book and my techniques of doing so vary from puzzle to puzzle.
However, what I do is this: when I start a new puzzle, I go through all of the numbers, starting with the 1's and working my way up to the 9's to see if there are any obvious placements. Then, I check each row and each column to see what's missing from that particular row/column. Then, I check each square of 9 cells to see what's missing and where I can fit it in.
As I mentioned, I do mine on paper with a pencil (and eraser!), so I write the missing numbers for each row at the side of the row and those from the columns under each column. As for the squares of cells, I draw a mini grid at the bottom of the page and list all the missing numbers from each square in the appropriate section - kind of like a giant noughts and crosses grid.
Other than that, I do exactly what it says in the book and on the website.
Generally, if I stare at the puzzle long enough I spot what's missing and how, logically (i.e. it can only be that number in that cell), it can be fitted in. It does eventually come to me - and is usually staring me in the face!
Obviously, given that it can take me a whole weekend to solve the one puzzle, it's not a fool-proof method - I'm sure that there will be other, more efficient ways of solving them - and I certainly don't claim to be an expert on the subject. This I can say, the more tired I am, or for that matter angry (won't go into that!) the longer it takes me to solve, because I'm distracted and not concentrating fully on the puzzle.
I'd just like to state that I do not - in spite of the fact that I use pencil and paper - write in a number on the off-chance that it could be that and then rub it out in the event that it's wrong and try something else (which is trial and error). I don't place any number unless I've got a logical reason for doing so - or so I think at the time! - and in the event that I rub it out it's because I got the logic wrong not because I'm trying it out.
As it turns out I haven't done one in over a week. I've never done one from the Times so can't comment on them, I do the ones from the book. I genuinely don't look at the answers, even when finished. I check rows and columns and assume that if they are correct the puzzle is solved. I'm concerned only with my own entertainment and gain immense satisfaction when I do eventually solve one that has been holding me back for the whole weekend (which is why I understand your frustration!).
I do hope that helps you out. However, if I may suggest, it might be a useful learning exercise if you look at the answer to one of the puzzles that remain unsolved and then try to work out, from the answer, the logic behind it. I did that with one of the Daily Mail puzzles that was set over Christmas and was driving me mad. The Daily Mail has nothing to do with Pappocom but I thought at the time that the DM ones were the only puzzles available. The exercise was of limited use to me though (because I still couldn't figure out where they got the answer from), but it may be worth a try. The Pappocom puzzles
are logical - believe me, I felt the difference straight away - and there is only the one answer, so that might work for you.
It's really a personal thing. I'd rather use pencil and paper and work away at the puzzle until I figure it out - a whole weekend is the longest - a lot of people, as you can see, like to write programs to solve them which is a different challenge and probably gives a unique insight to them.
Let me know how you get on!
Luna