I concur with Dell ( now there's a first! ) that the vig is the same for $line parlays. As he noted they are what the term means a "let it ride" bet on the second leg if the first wins - similar to a let-it-ride conditional. He also denotes that spread parlays TYPICALLY have MORE vig ( though for 3 teamers ar 6-1 or higher the opposite is true ).
The advantage of them is their "compounding" nature and if you have an advantage then you compound it. There are many reasons not to play them however, even though most don't get them correct IMO. Line shopping limitations, money MGMT considerations, "honest or realistic winning % or +EV calculations" being the main three.
They don't help odds but they compound winnings and allow more ROI for winners. They will make losers lose more and faster though so you must KNOW which you are!
JMHO |