If anything they are much more time efficient than the alternative - grinding dozens of hours of leetcode in preparation of live coding challenges. In my experience that is pretty much the sole alternative.
There usually is a generous time frame for take homes of at least a couple of weeks. This is so much better and more flexible than coding challenges - not to mention coding rounds usually take several hours for the multiple rounds. Basically there's no time disadvantage at all for take homes.
Also speaking as a recent dad, so I get the time constraints.