Yo Mike: {car 33, where are you?}
When it comes to "tweaking," if you don't "tweak" and test and listen, then you can't accumulate a sense of "I like this or I don't like that."
In other words, as Gummbleman said, it kind of depends what your ears want to hear in a given vocal or music arrangement. Some tracks I've done I've used a large delay in the reverb just for the hell of it; it seemed that the words of the tune sounded better with the delay. But, as with most of us, the choice usually is what "we" like OR what the paying client wants to hear.
One thing I hear often on vocals put out by "stars" is that the vocal clips in one or two spots and the digital clip isn't what one is usually after.
Another instance, a very talented bass player friend of mine gave me DAT produced cassette of a three-piece band backing a fine singer ON A STAGE.
When I listened to the cassette the first time, it was very, very flat. The engineer did not put any reverb into her songs. I worked on that tape a bit and added YAM stage reverb and there was an big difference that was enjoyed by my bass friend and the gal vocalist whom I've never met.
When someone plays on a given stage, there is ambience and brilliance and, in MHO, a splash of the right reverb really helps the tracks sound cool.
Green Hornet
