A good way looking at over/under is using yahoo sports (hockey) and look at the previous games for team and see how they play in the first period. This breaks up the over/under only into the first period. I personally do not like taking the over 6 goals as in the case of Buffalo/Carolina and TB/Wash. Nor do I like taking the under 5 in the minn/calgary game. This gives you better odds and you will not push on the over/under and also don't have to worry about overtime. I have bet on games with overunder at 6 and have pushed several time or I lost the game with only 5 goals scored. I will take high scoring offenses and bad defenses and take the over in the first period. Eventually they will hit the over. I will also take the under in the first period with low scoring teams and those teams that play good defense. I am new to betting on hockey. I like to hear some comments about betting on the over unders in the first period.
I personally taking under 5, when the total is 5. I believe that a low total attracts the public to bet over, so the linesman can not make the total too low. The public already prefers overs to unders, my thinking is they prefer overs even more when the "5" makes it look like a good deal. I'm taking the under, and I'm going to shop around and get the best deal I can.
The books use very simple formulas to convert the game total and spread, into period totals and spreads. The best way to bet periods, would be if they come up with a new period line between periods. If you can come up with a more complex formula that is more accurate you can make money.