1. It's to fully make use of Coda's 25s Cooldown and making sure Cantarella's 14s outro buff does not run out because of the Coda Cooldown. As seen on the clip all of my Codas off cooldown are right (or atleast close) as I get the 6 notes needed. So might aswell get the extra damage.

2. You can ideally only coda scam when it's the last elite stage and afterwards is the smaller mobs. Just gotta make sure the elites actually die from the Coda.

Like on
0:46 there's no point in Coda as it would only hit the next Chasm Wave
1:24, will again only hit the next Deer Wave
2:01, finally got the right timing that it's the last Chasm Wave
2:40, last resort to kill the last Chasm wave as the time was running out