Of course, there are presumably situations where one's decision should change with the conditions. (I do get that there's a trade-off between retaining the ability to change with the right conditions and opening yourself up to changing with the wrong conditions though.)

The trade-off optimum is usually in making decisions aimed at producing concrete results, while leaving one's self largely free to determine how to achieve those results. But again, the level of required specificity is determined by the degree of conflict you can expect to arise (temptations and frustrations).