Most of the time it is accurate for single parts.. I print small parts in batches.. With acceleration turned on and lots of fast travel movements, the estimate can be off by as much as 40%. Easy test... print a bunch of 1/4" pillars with a 3/16" hole.
I think the easiest way to fix this issue is give the user control over a print speed time and fast travel time modifier in the process file.
There is room in the Advanced Tab Or Other Tab
Something like:
Build Time Estimate Behavior
Default Print Speed Time Modifier %
X/Y Movement Speed Time Modifier %
Then in the print time gui, post the software estimated time along with the users modified time.
and while you are at it.. Supply a modifier for the Auto Arrange Spacing.
I love the software...btw...