As heard on the Czabecast, don't forget about when to "buy" 1/2 points!
NEVER do I buy "on or off" a 3! That means you don't buy a "3" (to either a 2.5 or 3.5), nor do you buy a 2.5 (or 3.5) ONTO "3".
When you buy "1/2" point, instead or risking -110 (to get 100), you now risk -120. Win and of course no difference!
HOWEVER, "on or off" the 3 and you pay either -130 or even -135! Just not worth it. If I'm laying that much juice, I'd rather move to $line, or just skip that game!
But, you DO buy if it's a 4, 6, or 7! Magic numbers (maybe a 10 or 14 too, but larger numbers I may shy away from).
Less obvious, is I NEVER "buy OFF a number", but only off the "0.5"!
Buying from a half to whole (say from 6.5 to 7), you are essentially trying to "buy" a loss into a tie, or push. But buying from a 7 to a 6.5, you are trying to "buy" a tie to a win. What's the difference? Part mental and part math.
Mental: I don't feel I need to "Buy" a tie into a win. Whatever. If it's a push, it's a push.
I DO like to avoid a LOSS by "buying" off the loss!
Math: no impact when play is a winner. But if you lose, you are risking an extra $10 (per $100). So consider it a separate $10 bet (from your original bet).
If the line is say 6.5 and you "BUY" the line to +7. When the game comes in on exactly 7, you have "bought" you way off that loss and instead got a push. So instead of a -$110 losse you get a push. I say your $10 risked on the buy, got you $110 return (economist, opportunity cost here). So you got an 11-1 return on that decision to buy.
If you buy a line of -7 down to -6.5, by same rational, if the game came in on exactly -7, your "buy" of -$10 bought you from a push to a WIN. The $10 netted you +$100, or a 10-1 return.
Sure, nothing wrong with a 10-1 return, but I say:
1. Clearly 11-1 is better than 10-1, and
2. Given that you may lose 50% of your bets, I think the habit of buying "off" whole numbers is just a way to end up risking -120 instead of -110, and I can't to that. But, I will avoid some losses when games come in on the common outcomes of -4, -6, -7 by risking the -120 to get a tie not a loss!
Plus, I figure I'm going to win anyway :-)