The two checks on either side of the advance time rule
make it difficult to anticipate when scene start and end logic relying on time of day
or turn count
or values derived from them will trigger. A simple scenario to illustrate:
"Scene Logic"
Place is a room.
A firework is here. The firework can be ignited. Understand "fountain" as the firework.
Instead of burning the firework:
now the firework is ignited;
say "The fuse sputters and hisses, growing shorter by the second."
Fountain Spray is a scene. "With a whuff, the firework begins to spray a multicolored fountain of sparks."
Fountain Spray begins when the firework is ignited for one turn. [version A]
Fountain Spray ends when the time since Fountain Spray began is one minute.
When Fountain Spray ends:
now the firework is not ignited;
say "The fountain gutters out."
Test me with "burn firework / z / z".
I would naively expect the transcript of the test me to look like the following:
>test me
(Testing.)
>[1] burn firework
The fuse sputters and hisses, growing shorter by the second.
>[2] z
Time passes.
With a whuff, the firework begins to spray a multicolored fountain of sparks.
>[3] z
Time passes.
The fountain gutters out.
Instead, compilation on 6M62 produces:
>test me
(Testing.)
>[1] burn firework
The fuse sputters and hisses, growing shorter by the second.
With a whuff, the firework begins to spray a multicolored fountain of sparks.
The fountain gutters out.
>[2] z
Time passes.
>[3] z
Time passes.
Everything happening on the same turn is surprising to me, given the setup. The scene begins with the first check on the first turn and ends with the second check on the first turn.
A modification:
Fountain Spray begins when the firework is ignited for two turns. [version B]
Fountain Spray ends when the time since Fountain Spray began is one minute.
which yields:
>test me
(Testing.)
>[1] burn firework
The fuse sputters and hisses, growing shorter by the second.
With a whuff, the firework begins to spray a multicolored fountain of sparks.
>[2] z
Time passes.
The fountain gutters out.
>[3] z
Time passes.
The scene begins with the second check of the first turn and ends with the second check of the second turn.
Another variation:
Fountain Spray begins when the firework is ignited for one turn. [version C]
Fountain Spray ends when the time since Fountain Spray began is two minutes.
which yields:
>test me
(Testing.)
>[1] burn firework
The fuse sputters and hisses, growing shorter by the second.
With a whuff, the firework begins to spray a multicolored fountain of sparks.
>[2] z
Time passes.
The fountain gutters out.
>[3] z
Time passes.
The output looks identical to version B in this case but would not if there were every turn
rules that applied. The scene begins with the first check of the first turn and ends with the second check of the second turn.
Another variant:
Fountain Spray begins when the firework is ignited for two turns. [version D]
Fountain Spray ends when the time since Fountain Spray began is two minutes.
with result:
>test me
(Testing.)
>[1] burn firework
The fuse sputters and hisses, growing shorter by the second.
With a whuff, the firework begins to spray a multicolored fountain of sparks.
>[2] z
Time passes.
>[3] z
Time passes.
The fountain gutters out.
The scene starts with the second check of the first turn and ends with the second check of the third turn.
WWI 10.2 explains:
In theory any condition can be used to cue the scene - here, it’s “the player is in the Station for the third turn” - but it’s wise to look for a state of affairs which will last at least a brief time, because scene changes only happen at the start and end of turns.
but it doesn’t go into any detail about the placement of checks with respect to timekeeping.
It doesn’t seem like using time-related values to trigger scene changes is intended to be undesirable. I note that WWI 10.2 also introduces a time-based condition ("Train Stop begins when the player is in the Station for the third turn.
") as an example scene start condition, and WWI 10.3 continues with a time-based scene end condition, plus various time-related phrases.
WWI 10.4 introduces qualifying on the current scene in conditions, for use in rule preambles. But the every turn rules
won’t be checked until after the first scene change check of the turn sequence, so it’s important to know which check (first or second for a turn sequence) will cause the scene in question to start or end. Likewise for the if <scene> has happened...
and related conditions in this section.
If there were only one scene change check per cycle, then the reliability of time-related values as scene start and end triggers would be increased, because there would be a single stable value of each time-related value that could be applicable within the scene changes for a given turn sequence.