When you set , the SDK returns to its pre-4.1 behavior of lumping the session info for the previous session with the first hit of the subsequent session, which avoids the creation of an inflated visit.
This option causes an immediate drop in visit counts because inflated visits are no longer created.
For more information, see Using the char Set Property. Specifies the length of time, in seconds, that must elapse between the time the app launches but before the launch is considered to be a new session.
This timeout also applies when your application is sent to the background and reactivated.
One side effect is that the SDK might create a visit for the backdated hit.