I read a book where the author said something about not going thru with a bet he would have otherwise made if he had watched the line all week and it moved against him toward the end. He didn't say by how much, so it's assumed that even a half point would nix the deal. The book mainly discusses spreads, not O/U. He may have been speaking more of spreads than O/Us, especially key numbers, though he didn't say it had to be a key number moving against him in order for him to not bet. I presume his reasoning was due to him getting burned in the past more times than it was worth, so he just doesn't risk it anymore.
I'm wanting to get other takes on this idea, i.e. what your experience/policy is, on both spreads and O/Us. For example, if your numbers still have you winning if they hold up, even with a half point less of an edge than you could have gotten had you acted sooner, do you take on that extra risk in either instance? I've had several times when my numbers tell me what to do, and I lose a half point on the line being offered, and I still would have won (or lost) anyway. That half point moving against me hasn't made a difference that I can remember. On the other hand, I've had numerous times when holding out for a BETTER line, or jumping on one BEFORE it moves against me, HAS made a difference. I follow line movements on COVERS to decide whether to act now or wait.
As for tonights game, I decided to hold off after the line moved a half point against me when the reason I had waited was because I thought it might move a half point in my favor. I don't know that it was worth it. I had the under and will be very surprised if it would have made a difference, as it usually doesn't.
As for the book author, he may have been speaking ONLY of the spread, not totals, yet I've been practicing his policy for totals as well. Given my record so far, doing so hasn't helped me. If anything, I'm worse off than if I had gone ahead with the bet.