Simplify3D User Forum

Good day
Have searched the forums, but could not really get a answer.
In the "Other" Tab under speed settings - "Z Axis Movement Speed"
The popup states that it should match actual Z-axis movement speed between layers for accurate print times.
Must this speed be set the same as it is set in Marlin firmware #define DEFAULT_MAX_FEEDRATE?

Sure, that will get it close. Unfortunately, most printers these days try to move at extremely high speeds with a LOT of acceleration to limit the ramp up/down. This means that your print times will likely still be off by a bit, likely due to huge amounts of XY acceleration

I'm still a little unclear on this setting. Can it be used to reduce the actual z movement speed or is it only a numerical variable to try and produce more accurate print times?

Both. It changes the actual z-axis movement speed, and it can also get you more accurate print times if you make that speed more reasonable instead of using something silly like 12000 mm/min and then allowing max acceleration settings to override that