If the Full Scan was created by the local user as an On Demand or Scheduled Scan, then it will treat mapped drives as local drive and scan them since both the scan and mapped network drives are created under the user context. This is still the case if the AutoProtect option to scan network drives is disabled because that is an AutoProtect feature and does not have any bearing on local manual or scheduled scans.
If a Full Scan is created by an administrator on SEPM and sent to the client in a policy, the Full Scan will not scan mapped network drives since this scan runs under the SYSTEM context.