As above, this is a special situation, but one that seasoned professionals in Las Vegas practice as a matter of course. Say for example that you have bet a five-team parlay. There are four morning and early afternoon games "in" on the ticket. One game remains to be played and that one is a night game that won't start for a couple of hours.
You have two choices: you can sit tight and hope that the last game comes through and wins, in which case you will collect a tidy sum. If the team you have bet on doesn't cover the spread, you get to tell all your friends that you went 4-1 and didn't earn a penny.
Or, knowing how hard it is to win, you can hedge. This means that you take a certain percentage, either a quarter, third, or half the amount you stand to win if the parlay comes through, and bet it on the opposite side of your original ticket. Think of it as insurance.
In sports betting, there are blowouts, or "laughers." Your team jumps out to a 4- point lead and never looks back. The cheerleaders are playing by the time the game ends and they are kicking the other teams around the field. But these things don't happen often enough. Anything can happen and often does in sports as in life.
Your team is comfortably cruising along with a lead, and the opponent begins to nip away until the game is tied or the opponent has actually gone ahead. Hedging will make sure you get a return trip to the window.