It depends on what your goals are. When bulking carbs are a must. High GI carbs should be avoided except post workout, but low GI carbs should be consumed every 2-3 hours...in abundance. Everyone has thier own needs as to amounts, but carbs fuel the process of growth both indirectly and directly.
When dieting it becomes a little more personal of a matter. Some people swear by super low(<150g daily) or even no carb diets. Others prefer moderation and to keep some carbs in the diet. Everyones sensitivity to insulin is different and this requires different strategies for carb manipulation while cutting. It is a MUST while cutting that the carbs that are consumed be as low GI as possible with the exception of post training.