I’m afraid I’m going to have to take issue with your normally sage like advice Dave. (I still love you though)
I have several adjustment layers, cause it makes sense. One layer does a turbulent displace on everything below. The next one has an inverted feathered radial mask and blurs out the edges. A duplicate of this layer does so a little less, and lives above the other regular layers that need to stay more crisp and live above the previous edgeblurrerer. Then there is a glow adjustment layer, and a levels adjustment layer. I suppose these two effects could be on the same layer easy enough, but I like having them separate, and labeled in the comp, and when you hit “u” you only see the relevant keyframes instead of a bunch you don’t currently care about…
I can certainly see there is potential to get in to trouble with adjustment layers, but I quite like them and see no reason to use them only when I have to.
The copy/paste approach of putting the same effect on multiple layers has lots of potential issues too. A- I have a lot of layers. B- Some of them use a trackmatte from the layer above which would not play nice with the blurring effect. C- when you go to fine tune your effect, you have to make your adjustments on every layer, or set up pickwhip links, which are cool, and a good way to link stuff between precomps too, but when you’re dealing with multiple layers, some of which have Particular on them with a ton of animated channels, and you got a camera, and nulls helping to move it…, pickwhipping it good doesn’t sound so appealing.
Nowhere near as appealing as being able to say, this one layer here, exclude it from the Adjustment layers A, B, and F…