Captain Crocus

Зависимость есть не прямая.

Колин Мук. ActionScript for Flash MX: The Definitive Guide, 2nd Edition

When an interval is set to run less often than the duration of a tick of the frame rate, it will execute on the frame after the interval time has expired. For example, given an interval set to 400 ms and a frame rate of 10 fps (1 frame per 100 ms), Table 18-16 shows the frames on which the interval should execute.

Frame number | Total time (milliseconds) | Interval executed?
000 | 0 | no
001 | 100 | no
002 | 200 | no
003 | 300 | no
004 | 400 | yes
005 | 500 | no
006 | 600 | no
007 | 700 | no
008 | 800 | yes
009 | 900 | no
010 | 1000 | no

However, whether an interval runs more or less often than the frame rate of a movie, interval times are by no means guaranteed. In an actual test movie, the intervals in Table 18-16 may execute at frames 5 and 9, or even at frames 4 and 9. Code execution, Player rendering, and available system resources can all affect the actual timing of intervals. Where time is an important factor in an application (for example, in a game), functions should be written to account for variance in interval times.

Русского издания под рукой не было