Conventional wisdom is that you should pre-pay your mortgage — at the very least, you should break your monthly payment in half and pay it twice per month. Doing so can dramatically shorten the period of your loan and save you a bunch of money in the long haul. But as with all things, conventional wisdom isn’t necessarily the right answer. Liz Weston writes for CBS MoneyWatch, and addresses four reasons you very well may be better off doing something with that money other than pre-paying your mortgage. Plus, she uncovers some pre-payment scams you should avoid.