Garmin RV 760LMT arrival time to destination way off

In all the GPS (worth ####) and the navigator computer packages, there is a place to set your expected road speeds. The default setting for all of these is an impatient passcar drivers. Find that place and then reset those to realistic numbers for you. Then, as said above, check that the loaded routes did do some backtrack. The backtrack often happens when you include a stop but get the order wrong and not all the systems will alert you to this fact.

Matt - many years the navigator.