Somethinkitnecessarytodoso.Firstly,it'smoreeffectivetostudywithateacher'shelpthanbythemselves.Secondly,youcanhavemorechancestocommunicatewithteachers(therearemoreinteractionbetweenstudentsandteachers.).Besides,youcanmakeupforwhatyoumissorfailtounderstandinclassesonweekdays.Othersthinkitunnecessary.Foronething,studentscaneasilyformthehabitofdependence.Foranother,studentsneedtimeforrestandrecreationatweekend.What'sworse,attendingtrainingclassesorhiringtutorsevencausessomestudentsnottolistenattentivelyintheirregularclasses.Inmyopinion,whetheratrainingclassortutorisneededjustdepends.Ifyouarereallyveryweakatorinterestedinacertainsubject,maybeit'sOKforyou.Butbesuretochooseagoodandsuitableclassorteacher,otherwiseitwouldbeawasteoftimeandmoney.