Stepping songs at .1x speed rate or less?

[Shashakiro]

Precise technical accuracy is almost completely pointless at that speed. If you have to go lower than .3x just to figure out what the right note value is, then the section is either too fast for anyone to play without mashing, or too short for it to matter.

If you're going to spend serious time on a file, your time is much better spent testing it and improving the general fun factor, patterns, etc, than making sure that none of your arrows are a thousandth of a second off.