What we know is that burst only checks for raw danketsu points and that it takes 10 appeals.
From BT2 of the future to BT2 of the past: That's untrue.
A burst always takes 10 seconds and another second or so to restart with the appeal circles, thus effectively wasting more time depending on BPM.
I've also made a couple of new interesting observations, namely another BPM/ appeal one.
First lets start out with my original observation: Some songs end sooner than others.
2nd observation during a Fes: The AI stops appealing when your song is over, even if they just started bursting. They sure are polite for stopping.
3rd observation: Bursting takes around 11 seconds.
Because I'm a Visual unit user I'll be using the three 150 appeal Vi songs as examples.
First I clocked the time your final appeal chance happens for Ai LIKE HAMBURGER and MEGARE! starting from when the appeal circles start pulsating. It was around 1:34 and 1:40'ish respectively. With these values known it's easy figuring out the formula for final appealing being: (60(bpm/2))*appeals= time. We'll get 1:33.75 and 1:40.00 for both songs. Shiny Smile would take 1:45.88 with the formula.
Now back to observation 2 and 3. The AI stops appealing when your song's over and bursting takes around 11 seconds.
If you're playing a Fes and your opponent is Shadow★Mars, Hibiki using Shiny Smile, you'll know that her song takes 1:46'ish. If you're using Ai LIKE HAMBURGER your song ends at 1:34 so if you can do a burst at 1:23 you effectively stop the AI from appealing for 23(!) seconds.
If we modify the earlier formula we can make a formula for lost chances; ((appeals/2)/60)*seconds= appeals lost or ((150/2)/60)*23=28.75 appeals. For a song with 150 appeals that's around 19% scoring potential lost at best.
Also, Shiny Smile is a mere 170bpm song, whereas Hamburger is 192 even though they have the same appeal chances. We already know voltage rise is based on the amount of appeals during a song and the max appeals it possesses. Or 192/170*100-100=13% faster. What this tells us is that Hamburger gains voltage faster than SS with the same conditions and can do a burst when SS is still stuck at 170/192*100= 89% voltage.
Back to the formula ((appeals/2)/60)*seconds= appeals lost.
If we want to see how many appeal chances you lose during a burst we'll use 11 seconds (I don't have the actual value, so let's assume 11 is correct) and we'll get the following results:
Shiny= 15.6, Megare= 16.5, Hamburger =17.6
This means that even though they have around the same scoring potential without using bursts, Hamburger loses 2 extra appeals when compared to SS because it's faster.
With the knowledge we obtained with final appeal chance time, appeals, bursting and voltage it means that songs with the same appeals and a higher bpm is more suited for Fes's but for general scoring purposes the same amount of appeals and a lower bpm is better for general scoring purposes because its relative bursting time is less, thus wasting less appeals.
Useless info:WaO loses 23.3% of scoring potential when GMW bursts at 1:19, though no AI opponent uses WaO as their song.
GO MY WAY!! 1:30.67
relations 1:41.41
Me ga Au Toki 1:40.14
Kiramekirari 1:40.00
Kosmos, Cosmos 1:41.31
Meisou Mind 1:34:74
Do-Dai 1:45.26
My Best Friend 1:31.72
Shiny Smile 1:45.88
my song 1:41.54
i 1:42.86
LMG 1:31.56
Hamburger 1:33.75
Nanairo Botan
SMOKY THRILL 1:38.63
THE IDOLM@STER 1:30.00
MEGARE! 1:40.00
WaO 1:47.78
Honey Heartbeat 1:41.41
READY!!
Kami SUMMER!!
Vampire Girl 1:42.62
L.O.B.M 1:38.82
Colorful Days 1:30.57
I Want 1:41.12
Shiny Smile 1:45.88
MEGARE! 1:40.00
Hamburger 1:33.75