People that put compression on everything either A) are punks who don't know how to set levels in a mix, B) are working with people who can't play worth a damn, C) are chumps who can't hear what they are mixing cuz they're deaf or their monitors suck, D) are just ignorant and don't know any better because they've never played music themselves, so don't understand the importance of dynamics in expressiveness of sound, and read too many magazine advertisements.
The less compression you can get away with, the more expressive your sound will be. The reason why folks like stuff all kinds of compressed for dance music is that they try to drive sound systems to their absolute limits in SPL, even if it sounds like crap so that it's just loud. It's so they can keep up with the next record and make it cut through no matter how loud the other record is, or how little the DJ knows about running a mixer, especially one with an EQ on it. When I hear loud but sounds like crap, know what I do? I put the record back in its sleeve and leave it for the next chump while I go to the counter with the older bumpin stuff that might be a little quieter, but sounds so much more alive. As for my own stuff...it all depends on what I'm aking, and where it's gonna be played.
There's no cut and dried answer. Having the differnt ones is nice, but you don't need to use them all every time, and in fact I would try to avoid it as compression typically adds distortion.
Ape