BaseCamp Nuvi 1490 LTM ReCalculate Routes

Several months back a firmware update produced a ReCalculate button option on the Nuvi when importing a route from BaseCamp. I have pretty much confirmed, the button does not allows me upload a route from BC, not ReCalculate, and get the same route on the Nuvi I had in BC. My question is does the recalculate button do anything except allow you to change preferences on the Nuvi and recalculate? It appears to me that if I have a route with only a starting and ending waypoint, BC sends several additional waypoints to the Nuvi. The Nuvi seems to recalculate as part of moving the BC route to the Nuvi route folder using current Nuvi preferences but I don't think the Nuvi is using anything except the starting and ending waypoints. Can anyone expand on the Nuvi recalculate button relative to an uploaded BC route? If I add a third waypoint or a shaping point to the route, the Nuvi will route through all three points but it appears to me the Nuvi will not use the additional waypoints BC adds to the route.

Thanks