The long-term direction of a currency pair is often determined by the economic fundamentals and Geo-political realities of the country in question. These fundamentals might include the interest rate policy of the central bank, balance of payments numbers and the government's general political stance, to name a few. If a country’s economy is doing well and there are no extenuating matters, then its currency should appreciate against currencies with weaker economies.
Doing fundamental analysis like this gives a trader a long-term outlook on a currency and affords him the luxury of not taking multiple small losses, such as those that occur when tight stop losses are used. All he has to do is await for pullbacks to go long on the currency. If a trade goes negative, it can do so to a greater degree than would be possible if high leveraging was used.
However, there are exceptions to this rule. If a correction is imminent, it might be prudent to take a small loss by exiting previously negative trades and reverse positions to take advantage of the changing trend.