There's a couple schools of thought on this one. One is weekenders give you weekends. That isn't always a bad thing. Get good weekenders and you have a good product that would attract weekend listeners. The downside to having the same shows, like the same DJ on the weekends, as a voice tracked show vs their live show during the week is that the loyal listeners have already heard those routines or chatter and probably will tune out. With a weekend show, you might make some changes to the music lineup so to add some other songs that don't get played during the week to give the weekend show its own format, so to speak so that it has a different yet same sound as the weekdays. Also, if you have the radio on all week long at work do you really want to hear the same stuff on the weekend? Work routine vs Off time routine. Same with Rush. He's entertaining, but once you've heard the stuff, a rerun would be boring and a definite tuneout for most people.
WHYY-FM does not air the same programming on Saturday and Sundays as they air during the week. I enjoy their weekday programming, but look forward to hearing Car Talk, You Bet Your Garden, and Prairie Home Companion on Saturdays. I would not listen to reruns of any of the weekday shows any more than I listen to reruns of Rush. I used to tune in to WILM on Saturdays to hear Monica Crowley, but once they started Rush reruns they lost me.
In WILM's defense, they do air a local home fixit show, a local money/politics show, and Kim Kommando giving their morning and early afternoons on Saturdays a difference from their weekday programming and I do tune in sometimes to those shows, but then they blow it with Rush Saturday afternoon. The other problem with Rush's so called week in review is some of that stuff is old news by time Saturday gets around and the story may have developed much further than where Rush is with it on Monday of the past week making it seem even more out of place. So if I were running WILM, I'd go back to Monica or some other live Saturday talk show and drop the weekend Limbaugh reruns.