I think she misses at least one aspect of this idea of worship as a "time-waster," that is, the idea that "liturgical time" is outside of mundane (earthly) time because it is oriented to the clock of God's Kingdom. Liturgical time brings the past into the present, as we recall the Last Supper, Christ's death and resurrection; and it brings the end of time (eschaton) near to us, giving us a glimpse of the worship of God that takes place perpetually in heaven around God's throne, as well as a foretaste of the heavenly banquet that awaits us. (Actually, she might pick this up somewhere - I confess I haven't read the entire book.) In this sense, too, worship is a waste of time - by the world's economy of time, we could be doing better, more productive things; also, by the Kingdom's economy of time, it is a con-fusion (literally "to run together") of times. Or, more specifically, it is the subversion of kronos, linear or sequential time, by kairos, which is "God's appointed time," the time of an event, of the happening of something special, something crucial. "Kiaretic" time is, even by etymologic similarity, the time of the Cross (crucis), where earthly time stands still in the wonder of this meeting, this intersection of heaven and earth.
Still, perhaps there is something to thinking of worship as a waste of time in the most literal and mundane sense. Adam Kotsko, a former Nazarene, has expressed this much better than I ever could:
"I don't want a worship experience at all. Or maybe I do. I want to stand-sit-kneel every so often, I want to say the words the congregation is supposed to say, I want to sit patiently through the bad homily, I want to taste the wafer and maybe the watered-down wine -- I want to make sure I don't forget. It's nice to be reminded, every so often, that this stupid and pointless thing is happening, and to participate in it, to waste a half hour on it and walk away with nothing. I think that's important."(Excerpted from his post, which you should read if you have a moment.) As much as a I talk about, think about, write about, read about, and participate in liturgy, I confess there are many times when what I feel is precisely nothing. And as a good Nazarene boy, I can't help but think, "Well, why did I even bother?" If I leave feeling even more alienated from God and perhaps even from other people; if I leave with more of a profound sense of God's absence than of God's presence, well, then isn't something wrong? With me? With the liturgy? Maybe the music wasn't good enough. Maybe the sermon was weak. Maybe my "heart wasn't in the right place."
Even then, I have to believe that it matters, that what I've done by submitting myself to these strange practices of Christian worship, even when it can only be described as "going through the motions" (so often the evangelical criticism of liturgy), is somehow significant, even if it doesn't seem to "make a difference." To worship in the absence of God demands a lot more of faith than to do so in God's overwhelming (if occasionally manufactured) presence...does it not?