You can put the effect you need onto a null object as well as on the standard layer. Then expression link the various properties of the effect on the standard layer to the effect on the null object. If you do this with multiple layers you only need change the properties of the effect on the null object in order to change the effects accros all the standard layers.
Applying an effects favourite would work but if I wanted to change any of the properties of the effect I would have to go and change all layers (bearing in mind in the end I might have about 200 layers with the effect on!)
Dan I will try your solution tomorrow – Thanks
Andy