Ive been thinking about something lately that I'm sure there is a very simple answer for but i have not found it yet.
A lot of times in books let you parlay the over/under of a game with the spread for instance something like Team A -5/Over 55. So lets say in a matchup of:
Team A vs Team B with an over/under of 55
I am very confident in team A. My normal bet is $40. Straight up I would have to bet $40 to win $36.36(-110 assumed). Well what if i made a $20 parlay with team A/over and another $20 parlay of team A/under. A $20 parlay with -110
odds pays roughly $52 so now my $40 has a higher ROI. Is there something I'm missing? Naturally this would not be using the same book