However manually doing a multi is an outstanding way to bet and allows you to capitalise on overs, withdraw, change bet size etc. It does require some discipline but is worth the extra effort.
As Curious mentions most multi lock in unders early in the day and place bet ones produce horrific edges for the TAB. You would be far better taking win multi with the option of any 2,3,4 etc.
Multi’s are though a far better option than taking out dated product bets like Doubles, Trebles, Place 6, Pick 6 that produce divis often way below what a fixed odd multi would with a little effort.