It's not really a waste of time at all.
On the stages I play, i am stage right, the guitar is stage left, perhaps 5 or more metres away..we have a mic'd drum kit in between. the keyboard player is on my side of the stage and is DI'd into the desk, only monitoring on the stage wedges. Much of our music's tempo is dictated by the guitar delay so it's imperative that we can all hear it. Without wedges I wouldn't hear it at all. We all take cues from various instruments at various times throughout the set - it's very important to strike the right balance or you lose a lot of feel and stop working together as a band.....we're not a collection of individuals, doing our own thing, we're a band, we feed each other.