There's wasn't really any chance or lack of "control" if you knew the timing between Wildfire + Bioblast because Bioblast ticks at a fixed rate.
Wilfire + Bioblast + Scattergun = Wildfire pop into the enemy backline. If you had all 3 CDs available. If you and target(s) were lined up in the dream positioning. If they weren't paying attention and didn't guard at any point during the process.
Also, sometimes you just want the damage / pressure on a running target so a fire-and-forget of Wildfire + Bioblast was nice without having to worry about the enemy LOS'ing / moving out of range mid-cast of your Blast Charge.