Seven Circles

I am curious if anyone has tried the De LaMaza technique and achieved similar success (an enormous jump in strength).

Do some search.  His thesis is really old and there are lots of players here who weren't born when he wrote this thesis.  There are lots of blogs of people trying it and record their progress.

Generally, most people who completed the 7 circle have experienced some gain at least by 100~200 points ELO.  Also there are those who stagnate for several years reported gains after completing the 7 circles. 

However the "enormous jump in strength" (i.e. 400 pts in 400 days as described in his infomercial does not happen.)  At least it does not happen to any of the bloggers I have read, and I have read very many. 

I got hold of the book a long time ago, and thought about reading it, no idea what to expect. I enjoy reading chess books, before that I read Silman books, best lessons of a chess coach, my system and so on. But this book seemed different, as it wasn't trying to teach me chess with practical examples but rather try to force me to improve through 'willpower'. I didn't find that fun at all, and forgot my attempt at it later. What I do to improve my tactics, is develop a tactical thinking technique, read tons of other chess tactics books (like Forcing chess moves, 1000 checkmate combinations, perfect your chess) and I have had more fun and I think I notice my results better that way. 

I do not think one needs to be in the amount of work he did for the same result.

A fairly lengthy commentary on the de la Maza book can be found in the 2006 revision of Secrets of Practical Chess by John Nunn.

https://web.archive.org/web/20140708094733/http://www.chesscafe.com/text/secprac.txt

"... there is no doubt that intensive study will result in improvement in virtually any area. The large question mark is whether it is better to spend the time on the 'Chess Vision Drills' and 'Seven Circles', or on standard chess training methods. I would certainly recommend the latter. ..." - GM John Nunn (2006)