If you are talking about trend following, a longer time frame requires that you set your stop loss lower. If you get stopped out your loss is bigger, but if you don't you are rewarded with a long trend. Win or lose, longer frequency trading takes less work.
Or "wider", anyway, if not "lower" (there are short trades, for which you'd often set it higher?). Different risk-exposure in different time-frames is completely logical, reflecting the fact that (according to what constitutes one's edge) longer time-frames may give fewer and more reliable trading signals, and one normally derives risk-exposure from expectancy.
http://www.vantharp.com/tharp-concepts/expectancy.asp http://www.learningmarkets.com/determining-expectancy-in-your-trading/ http://www.tradermike.net/2004/05/trading_101_expectancy/