Rule of thumb for decoupling individual op amps vs a cap across the rails?

[eatswires]

I'm designing something with a few op amp gain stages, 3 buffers and 5 amplifiers (lots of splitting, blending, and clipping). In all the designs I look at for reference I usually just see something like a 100u cap across the rails to deal with DC ripple. However it seems that decoupling individual op amps across their +v and ground is seen as more of a "best practice" but I rarely see it (maybe I'm just not looking at the right schematics).

I'm wondering if there's a rule of thumb for when that starts to be important, or is it just generally a better thing to do? Is it just that simpler circuits can get away with a more generalized solution?

 

[Alan W]

I can’t give you any useful rules, but if a circuit doesn’t have 100n bypass caps for each opamp, I tend to throw them on the backside, leaving the socket legs longer on those two pins. Typically, you want them as close as possible to the device.