You are right, sorry I made a mistake. I confused myself with the value of the health bar that some time ago people were arguing to want get back (the 240 setting).
And yes, the refilling of the health bar in the training mode can mislead.
In a kill combo you want to deal a minimum of 300 points for it to be considered a kill combo. I have a combo that does exactly 300 in DZ that i can post later but in training the health bar visuals can be very misleading so you want to pay more attention to the number values.
Normal health is 300 points. In training mode if you don't do damage in a couple seconds the health bar starts to refill (I did this in training and recorded with my PS4. I never play with inputs or data down because that is just plain annoying and i can't stand videos of matches with those).
From what I know the only problem is that the ground platforms on Danger Zone are random (contrarily for example to Lost World) so you can never know with certainty what you will get later, if a full blue platform or a full green one (I belive the only rule is that the platforms can't be immediately repeated).
Anyway this is very close to be a guaranteed kill combo!
If you can get a fully charged P+KT and slam an opponent into the green zones in Danger Zone you are damn near guaranteed to get a kill combo on all characters except Super Heavyweights.