guidance only

I'm learning the ins and outs of my new Nuvi 350 and came across this puzzling item:
In the settings directory, under "voice prompts", I have the choice "guidance only". On my KNA G510 that came bundled with Kenwood's entertainment system, I have the ability to turn off the voice's system status prompts. If I make a wrong turn or decide to take another route, I'm not constantly reminded that the GPS needs to "recalculate". The great thing about GPS is it can get you anywhere you want to go from where you are, even if you're somewhere else from where you told the GPS you wanted to be:).
Apparently, the Nuvi 350 doesn't think "Guidance Only" means the same thing I thought it does, since it's still telling me I did something that's causing it to "reclculate" whenever I decide (by choice or not) to ignore it's advice (actually, since I'm a guy, I'm genetically programmed to ignore the female voice, so more often than not, I don't "hear" Jill's commands:).
Does anyone know what Garmin means by "guidance only", and more importantly, how to turn that aggrivating "recalculating" voice prompt off?
Tnx, bfk