Adjustment layer

Drop one onto a track above your footage, add a grade, a grain, a vignette or a sharpen to the layer itself, and every clip underneath inherits the effect for as long as the layer runs. Change the setting once and the whole stretch updates. This is how most people apply a look across a sequence, and how you fade an effect in or out over time by keyframing the layer's own opacity. Two habits save trouble later: extend the layer only over the clips you meant to cover, and keep separate layers for separate jobs so a grain tweak never forces you to unpick the grade.