Iirc i kept using the primary appeal for a bit when a burst was coming up without raising the multiplier again.
Man I have no idea why I didn't think much about this earlier, with some simple testing it really doesnt seem worth keeping the multiplier at 1.5 for the burst. Even with maximum unity of 499 the loss at a multiplier of 1.46 with Chihayas burst would be 9*499-8,76*499 = 119,76 Points lost, which would in most cases be less than what you gain for using an extra Visual appeal. (assuming your primary stat is visual of course)
With the amount of variables I'm starting to think that calculating what method is best for the specific stats you have is the best one can come up with, rather than a general guideline for perfect play.
After the the burst, your mulitpliers will be in a bad spot. For example for Chihaya (PS3 version) they will be 0.9 dance, 1.0 visual and 1.2 vocal. So your secondary stat is already quite low, and the dumped stat you are not going to use anway is already at 1.2. If you use a memory appeal right off the bat after a burst, you reset all the multipliers to 1.1, so you can raise dance and visual, and the loss in vocal doesn't matter at all.
Hmm, so far I've been using the memory appeal right at the start of the song to get my multipliers to 1.1 at the start, since I was disregarding the earlier point, so Takanes burst appeal would net the same amount of points for visaul focused style as chihaya, since I kept building my visual multiplier back up to 1.5 and then after the burst the visual would start out at 1.1 and not require another memory appeal.
However with the previous point in the equation your way of playing is probably better. Honestly if I wanna make any calculation worth a damn, I need to check how exactly the multiplier build up works (I remember sometimes you would build up 0.04 and at other times 0.03 but I don't know what the exact pattern is).
Iirc every girl has exactly one personal song, but not every of these songs matches the stat you are focusing on. What the guide is saying, is to save the song which matches your focus stat for last. Of course, if 2 or even all 3 songs match, you can use them earlier. But to be honest, it's not necessary to use these songs. Iirc the only advantage of using the special song is that you have a higher chance to get a break and such.
Oh that makes more sense, though I still find the wording kind of misleading.
I wouldn't say that a higher chance for song status is something that should be overlooked too easily though, I found that on HYPER it was basically required to get a status to get to rank 1 and earn that S in the producer assessment. (maybe I'm just shit)
As for building up stats, iirc i did lessons on my primary stat until image level 10 or 11, then switched to my secondary stat until the image level is at least 14 on normal (since you need that to get an A ranking after the playthrough), and never did a lesson for the third stat, since i never used it anyway.
In my HYPER playthrough I actually got to image level 12 with just practicing my primary stat and assumed that it was probably maxed out at that point, I guess I'll test if you can go higher (counting dots on the dotted line seems like too much of a pain in the ass and being able to just base it on your image level would be nice).