Estimates take into account route lead-ins (once of course).
It shouldn't matter (much) if you ride the routes in the forward or reverse direction.
Take the accuracy estimates seriously. On a long ride, a 6% difference in
accuracy might mean a lot more distance or climbing than you wanted!
Routes that are not loops only appear if you can accrue enough distance and climbing
to complete your ride by the end of the route, since you can't do multiple laps.
Estimates are based on the overall slope of each route.
It doesn't know where the hills are located within each route.
So if an estimate tells you to ride a fractional portion of a lap,
be aware that depending on that route's specific incline profile
you might need to ride a little bit further than indicated
in order to match your exact distance and climbing goal.