why do all of my runs in everything go to hell in stage 4
ZUN has his ways with stage 4.
SoEW Marisa: freakin' orbs.
LLS: Reimu fights Marisa, Marisa fights Reimu.
MS Yuki and Mai: Fighting both, and depending on who you kill first, you re-fight the other with reset health.
EoSD Patchy: Different spells depending on character and shot type, along with difficulty.
PCB Prismriver sisters: Depending on who you choose, different opener. And depending on who you shoot the most on first spell, different person = different attacks.
IN stage 4a or 4b: Again, depending on who you choose you get either Reimu or Marisa.
MoF Aya: Can't say much about her. Though she showed up on 9th game before the usual danmaku game type.
SA Satori: Recollection spells are different for every shot type.
UFO Murasa: ANCHORS!!!
(games 1, 3, 9 and non-whole numbered games don't count, since they're different)