Potion duration depending on what it does (explanation inside!)

For example, a potion of Fire Resistance's duration should only drain depending on how long you are in lava, Regeneration on how many hearts healed (for example, healing a certain amount of hearts) Slow Falling on how many blocks fell, etc etc.

And make sure there are gamerules to turn this on or off! Something like /gamerule potion-Regeneration, potion-SlowFalling, etc