The Donkey, let it be understood right at the start, is me.
I came to Sudoku rather late in life - I've been interested in the idea for years, but I swerved the craze (was it a craze? - is it now an ex-craze?) because I know myself too well; I always knew I would get hooked and would waste far too many hours - I find the puzzles very compelling, and the perfection of the game system has a strange beauty and rhythm. Love it.
This started in earnest in 2016, when I bought the first 4 of the Telegraph's Sudoku books to take on holiday to Austria. I very quickly became addicted, and got a lot of pleasure from them. I invested in a good-quality propelling pencil (Faber-Castell Grip-Plus model, 0.7mm lead, lose the pocket clip, keep a supply of fresh eraser inserts...) - with the pencil tucked in the current page of my current book, I'm a happy bunny on train journeys, in dentists' waiting rooms - you name it. I don't claim to be particularly brilliant at Sudoku, you understand, but I like to think I'm not bad, if a little slow sometimes.
The Telegraph books are structured so that the puzzles are graded - they start off "Gentle" and then get progressively more difficult, going through "Tough" (I can't remember all the actual grade titles) until they get to "Diabolical" at the end. Problem is that the faster you bash through the easier ones, the quicker you reach the near-impossible ones at the end. The end-state of one of my Telegraph Sudoku books is that I am left with only the very hardest puzzles, so that if I pick up an almost-finished book I have maybe a 20% chance of solving the next puzzle.
Thus I have started each new book before the previous one was finished - basically because I am not capable of finishing it, but also because regularly failing to solve the next puzzle is not entirely gratifying (though one appreciates a challenge, of course).
I believe I have now "finished" (more accurately, "had enough of") Telegraph books 1 to 7, though I suspect I never did purchase Vol.6. I've chucked out the "finished" books, and now started looking to see what further volumes the Telegraph is offering. It was only when I started looking that it suddenly dawned on me that, since there is no way I would ever remember, or even recognise, a particular puzzle I had already attempted, it would be perfectly feasible to start again with Volume 1. Thus I have ordered books 1 to 4, though Amazon helpfully protested that I had bought these same books just two years ago. One big plus (especially for us Scottish enthusiasts) is that the earlier volumes are available through Amazon's Marketplace, new, at 30 pence a pop, rather than the full price of £5.99. You do get stiffed a little for P&P, but it's still a big saving. Better and better.
So I've ordered up the same books again! If everything goes well, there's no reason why I couldn't order them up yet again sometime later. All right, I could get someone else's Sudoku books instead, I suppose, but I know and trust the Telegraph's gradings and organisation.
In passing, I was intrigued to note that some dealers on the Marketplace were offering even cheaper, used copies. A used copy of a Sudoku puzzle book? - if they're anything like mine, they will be full of scribblings, and filthy with the rubbings-out which are an important part of the solution. Sounds a bit dodgy to me - would you buy, for example, a second-hand paperback book of crosswords?
Anyway - Groundhog Day puzzles should start here in a week or so.