I’m not sure that is what I was referring too, but they could have changed things in the app since I last used timed shots. I did go to power on my drone last night to check, but is when I discovered it will no longer pair (see dedicated thread here) so I guess no fireworks pics for me this year.
You can do timed shots and it will just carry on taking a photo until you turn it off if you set it here. But equally burst may be better for fireworks, much like it is when working with animals on a normal camera. Or just smash the shutter button! 
