This series, https://archiveofourown.org/series/15348 (17 total associated fics and ficlets), contains quite possibly my favorite, slow-burn, subtle development of Mystrade, where neither is out of character, yet Mycroft manages to be sympathetic despite his reserve. It starts post-Reichenbach, except for the pre-Baskerville Mycroft-musing ~prologue~ which establishes the chess metaphor.
But it's not just Mystrade, either, with great characterization of John, too, the main focus, obviously, of John Watson's 12 Things Happy People Do, a bittersweetly satirical look at trying to apply self-help advice.
Then Sherlock finally returns in definitely-NOT-low-conflict Part 13, The Empty House (written pre-season 3, this has a great headcanon for Moriarty's web, with a tip o' the hat to ACD canon), after which the rest are wholly or primarily Johnlock, though [theoretically] all set in the same 'verse, back to low-conflict.
It took me only a few pieces to decide I was liking this series ever more, and that impression remained true through its whole rich mix, though I kind of wish it weren't just posted here as a single work.
N.b., the first arc (the directly Scotch-titled ones) could really be chapters of one Mystrade fic, but the author didn't realize that's how these supposed one-shots were going to turn out. On second thought, maybe that's all the "librarian" actually intended this listing to reference? No, on third thought, that wouldn't be anywhere near "572 pages"! (My own 300wpp calculation puts the whole series at just under 400 pages.)