Atar is only for getting into the course you want, as long as you get into the course you want then you've succeeded. If you can't change your decision there no point to dwell over it.
Its an extension so it most likely will be good scaling. Before you pick it think about the workload and if you have a genuine interest in the subject. Science ext, from what I've heard and memory, its has a lot to do with data and stuff (I think).
I used YPT and I thought I turned off the timer, however I woke up to it still going through the whole night 💀. The timer like got up to 15 hours or something and I’ve had this happen multiple times.