if u r going to use the same session object in subsequent
servlets, u can use either method!!
getSession() or getSession(true) gets the current session object or
creates a new one if there is none!
getSession(false) gets the current session but, if one doen't exist already, it
doesn't create a new one.
if u r talking about creating a session object for the first time i.e. in the first servlet, then using getSession() or getSession(true) is a better option as u'll get a new session object even if there wasn't any. whereas, getSession(false) won't creat any, and u won't have any session object to pass session values to the remaining servlets!!
hope that cleared ur doubt!!
rgds,
Shashi