Examining "Once Per Day" in TFT: Solution or Problem?

[Skarg]

I have done that sort of tracking, mainly when dealing with GURPS healing spells which have penalties for casting them more than once per day per caster per subject (and other house rules I added), but also with things like magical effects that last hours or days (in TFT, potions tend to last one or more hours or a day).

I don't quite get what you'd propose as better than what seems to me the obvious way to handle it. I memorize and/or write down the time of day when the effect started and/or will end. Then I keep track of time during play, often in minutes or hours rather than days, letting the players know and/or approve time advances as seems appropriate to me and to them (i.e., I often use a suggestive tone of voice and slowly say "an hour later . . ." giving them a chance to say, "wait, I want to X..." or whatever, so we collaboratively advance time.

There is an issue that can come up about how accurately the players know what time it is. And I also would tend to house rule that magical durations tend to vary a bit randomly off exactly 24 hours to the second, anyway, unless there's some compelling reason that should be reliable and consistent for every casting or potion. At least, enough that, combined with the roughness of times spent in travel, rest, breakfast, etc, I can write down a time 24 hours away in minutes rather than precise seconds.

And, there's the question of whether a caster/drinker/item-user knows somehow that a period has expired 24 hours later the instant it happens, or whether they get any warning it's about to happen, or not, for each spell or potion effect. If the effect is obvious (I can't see now so I bet my Dark Vision potion wore off), then it's clear, but not necessarily for all. With GURPS healing spells, for example, I decided the 24 hour danger period should be a little fuzzy and unknown unless someone made a successful diagnosis or magical analysis, and they wouldn't know the exact time if they had a method for that, to add to the fear & uncertainty of pushing the envelope on those powerful spells.