Alright, maybe all these brain exercises aren't worth doing. According to this article from the Boston Globe, there is no proof that brain exercises help make you smarter at all. The study shows some minor long term effects in most areas except in the area of memory.
However, studies also show that in the short term, these exercises can actually help you out. I know that when I practice memorizing a deck of cards it improves my ability to remember cards played during a euchre game. And studies also show that juggling improves your brain.
So, you decide. Maybe training your brain will help your euchre play but on the other hand, maybe it won't. Maybe you might be better off having an extra beer during the game. It might not help your play but it might make you feel better about losing.