Because keeping that level of consistency for that long is the problem, at least for me. It's not like I can't do it, on a good run I could do it with 4 or less deaths. The problem is not derping and losing those lives in a stupid manner every time. Like i said, I've carried 3 lives into Stage 5, and then lost all of them and the extend Sanae drops to stupid things, having 0 lives for Stage 6.
How well I do on the later stages is inversely proportional to how well I do on the early stages-no death 1-3=not even reach Aya somehow, and 4 deaths on stage 3 I got a 1 death Stage 4 (and then threw the run on Stage 5).
It's something I should be able to do, even on most sessions, but I haven't even been able to do it once. It's just a matter of time, but losing even one attempt to exceptionally bad luck everywhere really annoyed me. That's all.
Oh also yet another promising run thrown on Stage 5 with 4 deaths, and then I go and perfect the stage in stage practice. Twice in a row. And I did it before the attempt as well, knowing I usually fail there for stupid reasons. Maybe I should switch to MarisaC strats for faster boss kills...but at the same time I want to do what I set out to do back when I perfected Stages 3-5 in a row, LNB with ReimuB. Just sucks that I can't hold together a run long enough to even get a real shot at Stage 6...
edit: that replay looks similar to most of my attempts, but with less fail on stage portions and more derpy boss deaths with the same result-facing down Stage 6 with 0 lives, regardless of how the start goes. 0-0-4-1-3, 0-0-0-6-?, 0-0-2-5-1, doesn't matter, the numbers never add up in runs yet in practice, they do.