I personally advise against the use of presets and think they are more of a detriment to one learning how set up a device, whether harware or software- based, in the overall mixing process.
Agreed. While I don't think it's detrimental to use, as Chaz stated, presets you build yourself, I agree that reaching for a "generic setting" or a plug setting programmed by someone else can result in sidestepping the most important thing, and that is learning and becoming familiar with what that particular processor actually does.
Caveat: if you're just a hobbyinst having fun, and don't care about learning the engineering side, go ahead and use 'em...
But don't expect to make you sound like the label the preset claims.
As Yep mentioned, in regard to EQ or dynamics processors, the variables are sooooo wide (mic, vocalist, room, etc) that while it might get you a
little close, (but probably not) ...well, to put it simply, a "Peter Gabriel" EQ preset isn't going to make you sound like Gabriel.... nor will it take into account the U47, 67 C12 or other hi end mic he used, or the acoustically tuned room, or the rack of 1176's, LA2's and Fairchild 600's, or... Tom Lorde Alge on the mixer...
It's best that you work with your own presets, build your own, and in doing so, learn the in's and out's of what that particular processor actually does.
Have fun!
D.