Milliseconds

[adicoto]

For audio synchronising (i've done some) 5/100 (0,5/10) of a second it's enough in terms of steps to do a good synchronisation.
For subtitling (i've done some) 0,5 seconds it's enough in terms of precision. Besides, the most important subtile creating softwares works with "click and insert framenumber (or time)" .

Time counter can increase with 1/1000 of a sec. it's not limited by the framerate (time it's time, it's only limited by the use of time displaying) but it will be useless to display continously such an info.
Around 100 fps (1/100 sec) it's the highest framerate that the human eye it's comfortable with and can be folowed, so everything beyond it's useless.