I just started using Simplufy3D again with the new update and I am wondering if there is a way to adjust the time estimate as it seems to always be low by 10%-20%.
There are too many variables to make it accurate; you'd need to calculate a curve based on your printer's acceleration and jerk settings as well as printer speed. I my case I just graphed the predicted vs actual print time for about 50 prints of various sizes and that gave me a good way to predict times.
OK, it's just in Repetier host has a feature where you can just add or subtract a % and after several adjustments I had it pretty darn close (maybe 2-5 minutes off on an 8 hour print).