I use a similar method, but because my Sorcerer uses Control Flames, we ruled that the Light gets brighter by doubling the size of the flame, which also increases the Damage Die Size (1, 1d2, 1d3, 1d4, 1d6, 1d8, 1d10, etc), however, each time the flame is enlarged that way, it burns 2x faster, so 600 turns becomes 300, 150, 75, etc. I have it's "Health"(duration) assigned to a Bar on the Default Token, and I can track the Control Flames using not only the Maximum Health, but the Status Effect Icons as well. Without linking it to the Character Sheet's HP Stat; I'm capable of retaining the @{target|1|character_name} calls, without causing problems with the other Tokens dropped by this effect. Usually we completely consume the Torches, but, should we keep one that was previously Lit, I have the players make note of it's Current & Max HP so I can multiply it back out. I don't even need to round() the HP because it's always going to be a whole number when you remove Control Flames, unless you dimmed it, at which point, you simply tell them it sputters out on the turn it starts with less than 1. This method can be used to make a Torch a viable Weapon, as 6 uses of Control Flames makes the Damage Die a 1d10, but takes 2 Casters, the Torch Light would be almost a Quarter Mile Radius, & the Torch wouldn't last very long either, (600, 300(1), 150(2), 149, 74.5(3), 37.25(4), 36.25, 18.125(5), 8.0625(6), 7.0625) 7.0625 Turns at most of 1d10 Fire Damage for 2 Casters on a new Torch that someone else lit. It's a well balanced ruling, because if we do that outdoors, we might attract a few Dragons amongst a wide variety of other things, since the Dim Light goes out for almost a full Mile Across (~0.49 Mile Radius), limiting such tactics to deep caves with lots of twists and turns.